共查询到20条相似文献,搜索用时 796 毫秒
1.
CD23 (the low-affinity IgE receptor) as a C-type lectin: a multidomain and multifunctional molecule 总被引:5,自引:0,他引:5
Kijimoto-Ochiai S 《Cellular and molecular life sciences : CMLS》2002,59(4):648-664
This review, regards the low-affinity receptor CD23 as a C-type lectin and compares it with other C-type lectins and C-type
lectin-like receptors. C-type lectins such as the asialoglycoprotein receptor, as well as the dendritic cell immunoreceptor
and the dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin on dendritic cell lectin, possess amino
acid sequences which interact with Ca++ and sugar, and many of them possess an endocytosis signal sequence that includes tyrosine or serine in the cytoplasmic region.
In contrast, natural killer receptors lack the Ca++ and sugar-binding amino acids but conserve homologous cysteines in the form of C-type lectin, and possess an immunoreceptor
tyrosine-based inhibitory motif in the cytoplasmic region which inhibits killer activity when they recognize the self major
histocompatibility (MHC) class I molecule. Since human CD23a form has a similar amino acid sequence, the possibility that
this sequence is an endocytosis signal or an ITIM is discussed. The function of the reverse RGD and RGD-binding inhibitory
peptide in human CD23 from the point of view of the relation between a C-type lectin and MHC class II molecules is also considered.
Received 21 May 2001; received after revision 28 November 2001; accepted 29 November 2001 相似文献
2.
D.B. Moody 《Cellular and molecular life sciences : CMLS》2001,58(10):1461-1474
T cells are well known to recognize peptide antigens presented by major histocompatibility (MHC) class I or class II molecules.
More recently, the CD1 family of antigen-presenting molecules has been shown to present both mammalian and microbial glycolipid
antigens for specific recognition by T cells. Human CD1c proteins mediate T cell recognition of polyisoprenyl glycolipids,
evolutionarily conserved phosphoglycolipids, which function in glycan synthesis pathways. This family of antigenic molecules
is particularly attractive for the study of the molecular features that control T cell recognition of self and foreign glycolipids
because natural polyisoprenols from mammals, fungi, protozoa, mycobacteria and eubacteria differ in structure. Moreover, these
naturally occurring structural differences can influence their recognition by CD1c-restricted T cells. This review of the
structural diversity and evolutionary relationships of polyisoprenoid glycolipids emphasizes those features of polyisoprenyl
glycolipid biosynthesis that are relevant to their functions as targets of CD1-mediated T cell responses.
Received 16 March 2001; received after revision 19 April 2001; accepted 23 April 2001 相似文献
3.
M. L. Rose 《Cellular and molecular life sciences : CMLS》1998,54(9):965-978
The immunological properties of human endothelial cells suggest they perform a pivotal role in acute and chronic rejection
following solid organ transplantation. In this review the basic features of acute and chronic rejection are described as are
the cellular and molecular requirements for antigen presentation. Traditionally, antigen-presenting cells are considered to
be bone marrow-derived cells. However, these conclusions have been derived from rodent models of allograft rejection where
bone marrow-derived passenger leukocytes are the only source of donor major histocompatibility complex (MHC) class II in the
grafted organ. In contrast, in humans, virtually all the microvascular and small vessel endothelial cells are ‘constitutively’
positive for MHC class II antigens. The phenotypic properties of human endothelial cells, their response to cytokines and
their ability to stimulate resting T cells are described. Unlike bone marrow-derived antigen presenting cells (APCs), which
utilise B7/CD28 interactions, human endothelial cells utilise lymphocyte function antigen 3 (LFA3)/CD2 pathways to stimulate
T cells. They activate a CD45RO + B7-independent subpopulation of T cells. Their effect on allogeneic T cells is compared
with other non-bone marrow-derived cells such as fibroblasts, epithelial cells and smooth muscle cells, which are unable to
stimulate resting T cells. Evidence is presented suggesting that release of MHC and non-human leukocyte antigens (HLA) from
endothelial cells stimulates an alloantibody and autoimmune response leading to chronic rejection.
Received 30 March 1998; received after revision 4 May 1998; accepted 4 May 1998 相似文献
4.
The recent development of functional models to analyze the early steps of the hepatitis C virus (HCV) life cycle has highlighted
that HCV entry is a slow and complex multistep process involving the presence of several entry factors. Initial host cell
attachment may involve glycosaminoglycans and the low-density lipoprotein receptor, after which the particle appears to interact
sequentially with three entry factors: the scavenger receptor class B type I, the tetraspanin CD81 and the tight-junction
protein claudin-1. Several serum components may also modulate HCV entry, while the recently discovered CD81 partner EWI-2wint
can block the interaction of the viral particle with CD81, potentially preventing infection in the cell types in which it
is expressed. After binding to the host cell, the HCV particle is internalized by clathrin-mediated endocytosis, with fusion
likely occuring in early endosomes. This review summarizes our current knowledge on HCV entry.
Received 27 June 2007; received after revision 2 August 2007; accepted 29 August 2007 相似文献
5.
CD100 is a leukocyte semaphorin 总被引:5,自引:0,他引:5
S. Delaire A. Elhabazi A. Bensussan L. Boumsell 《Cellular and molecular life sciences : CMLS》1998,54(11):1265-1276
CD100 was originally described as an activation molecule on the surface of human T lymphocytes. Its triggering through distinct
epitopes leads to different signals of costimulation with phorbol myristate acetate (PMA) or with CD3 and CD2. Interestingly,
CD100 was shown to associate with different partner molecules in T cells. First, CD100 can associate with CD45, a key molecule
with protein tyrosine phosphatase activity involved in T-cell transduction this association is physical and has functional
consequences for both partners. Second, CD100 interacts in its cytoplasmic domain with a Ser/Thr kinase for which it represents
a preferential substrate. Recently, CD100 was identified as a member of the semaphorin gene family. This family comprises
approximately 20 structurally related proteins. The first semaphorins were identified in the developing nervous system. Function
has been shown for only some of them and involves repulsion during growth cone guidance. Since CD100 was the first semaphorin
identified in the immune system, this raises the possibility of the involvement of members of the semaphorin family in other
physiological phenomena outside the nervous system.
Received 1 March 1998; received after revision 8 June 1998; accepted 8 June 1998 相似文献
6.
Interferon receptors and their role in interferon action 总被引:1,自引:0,他引:1
Interferon (IFN) proteins interact with cells through specific cell surface receptors, some of which have been purified and cloned. The alpha-IFNs and beta-IFN bind to a common receptor (type I), whereas gamma-IFN binds to a separate receptor (type II). Both types of high-affinity receptors have been demonstrated on a variety of receptors and the ways in which IFNs may affect cellular physiology and gene expression is discussed. 相似文献
7.
8.
M. Fontecave 《Cellular and molecular life sciences : CMLS》1998,54(7):684-695
Ribonucleotide reductases (RNRs) catalyse the reduction of ribonucleotides to deoxyribonucleotides. They play a pivotal role
in the regulation of DNA synthesis and are targets for antiproliferative drugs. Ribonucleotide reductases are unique enzymes
in that they all require a protein radical for activity. Class I nonheme iron RNRs (mammals, plants, Escherichia coli) use a tyrosyl/cysteinyl radical pair, class II adenosylcobalamin RNRs (prokaryotes, archaea) a cysteinyl radical, class
III iron-sulphur RNRs (facultative anaerobes) a glycyl radical. Here we describe the reactivity of these radicals with respect
to the natural ribonucleotide substrates as well as to a variety of enzyme inhibitors, radical scavengers, nitric oxide, superoxide
radicals and substrate analogues.
Received 3 December 1997; received after revision 26 February 1998; accepted 27 February 1998 相似文献
9.
The modular nature of apoptotic signaling proteins 总被引:9,自引:0,他引:9
K. Hofmann 《Cellular and molecular life sciences : CMLS》1999,55(8-9):1113-1128
Apoptosis, initiated by a variety of stimuli, is a physiological process that engages a well-ordered signaling cascade, eventually
leading to the controlled death of the cell. The most extensively studied apoptotic stimulus is the binding of death receptors
related to CD95 (Fas/Apo1) by their respective ligands. During the last years, a considerable number of proteins have been
identified which act together in the receptor-proximal part of the signaling pathway. Based on localized regions of sequence
similarity, it has been predicted that these proteins consist of several independently folding domains. In several cases these
predictions have been confirmed by structural studies; in other cases they are at least supported by experimental data. This
review focuses on the three most widespread domain families found in the apoptotic signaling proteins: the death domain, the
death effector domain and the caspase recruitment domain. The recently discovered analogies between these domains, both in
structure and in function, have shed some light on the overall architecture of the pathway leading from death receptor ligation
to the activation of caspases and eventually to the apoptotic phenotype.
Received 8 October 1998; received after revision 8 January 1999; accepted 8 January 1999 相似文献
10.
Sebastian Gliem Adnan S. Syed Alfredo Sansone Eugen Kludt Evangelia Tantalaki Thomas Hassenklöver Sigrun I. Korsching Ivan Manzini 《Cellular and molecular life sciences : CMLS》2013,70(11):1965-1984
In contrast to the single sensory surface present in teleost fishes, several spatially segregated subsystems with distinct molecular and functional characteristics define the mammalian olfactory system. However, the evolutionary steps of that transition remain unknown. Here we analyzed the olfactory system of an early diverging tetrapod, the amphibian Xenopus laevis, and report for the first time the existence of two odor-processing streams, sharply segregated in the main olfactory bulb and partially segregated in the olfactory epithelium of pre-metamorphic larvae. A lateral odor-processing stream is formed by microvillous receptor neurons and is characterized by amino acid responses and Gαo/Gαi as probable signal transducers, whereas a medial stream formed by ciliated receptor neurons is characterized by responses to alcohols, aldehydes, and ketones, and Gαolf/cAMP as probable signal transducers. To reveal candidates for the olfactory receptors underlying these two streams, the spatial distribution of 12 genes from four olfactory receptor gene families was determined. Several class II and some class I odorant receptors (ORs) mimic the spatial distribution observed for the medial stream, whereas a trace amine-associated receptor closely parallels the spatial pattern of the lateral odor-processing stream. Other olfactory receptors (some class I odorant receptors and vomeronasal type 1 receptors) and odor responses (to bile acids, amines) were not lateralized, the latter not even in the olfactory bulb, suggesting an incomplete segregation. Thus, the olfactory system of X. laevis exhibits an intermediate stage of segregation and as such appears well suited to investigate the molecular driving forces behind olfactory regionalization. 相似文献
11.
S. E. Grossberg J. L. Taylor V. M. Kushnaryov 《Cellular and molecular life sciences : CMLS》1989,45(6):508-513
Summary Interferon (IFN)_proteins interact with cells through specific cell surface receptors, some of which have been purified and cloned. The alpha-IFNs and beta-IFN bind to a common receptor (type I), whereas gamma-IFN binds to a separate receptor (type II). Both types of high-affinity receptors have been demonstrated on a variety of different kinds of cells but in relatively low numbers (102–104/cell). The relationship between IFN binding to receptors and the ways in which IFNs may affect cellular physiology and gene expression is discussed. 相似文献
12.
Low molecular weight protein tyrosine phosphatases (LMW-PTPs) are a family of 18-kDa enzymes involved in cell growth regulation.
Despite very limited sequence similarity to the PTP superfamily, they display a conserved signature motif in the catalytic
site. LMW-PTP associates and dephosphorylate many growth factor receptors, such as platelet-derived growth factor receptor
(PDGF-r), insulin receptor and ephrin receptor, thus downregulating many of the tyrosine kinase receptor functions that lead
to cell division. In particular, LMW-PTP acts on both growth-factor-induced mitosis, through dephosphorylation of activated
PDGF-r, and on cytoskeleton rearrangement, through dephosphorylation of p190RhoGAP and the consequent regulation of the small
GTPase Rho. LMW-PTP activity is modulated by tyrosine phosphorylation on two specific residues, each of them with specific
characteristics. LMW-PTP activity on specific substrates depends also on its localization. Moreover, LMW-PTP is reversibly
oxidized during growth factor signaling, leading to inhibition of its enzymatic activity. Recovery of phosphatase activity
depends on the availability of reduced glutathione and involves the formation of an S–S bridge between the two catalytic site
cysteines. Furthermore, studies on the redox state of LMW-PTP in contact-inhibited cells and in mature myoblasts suggest that
LMW-PTP is a general and versatile modulator of growth inhibition.
Received 17 January 2002; received after revision 22 March 2002; accepted 26 March 2002 相似文献
13.
Recognition of bacterial peptidoglycan by the innate immune system 总被引:15,自引:0,他引:15
Dziarski R 《Cellular and molecular life sciences : CMLS》2003,60(9):1793-1804
The innate immune system recognizes microorganisms through a series of pattern recognition receptors that are highly conserved in evolution. Peptidoglycan (PGN) is a unique and essential component of the cell wall of virtually all bacteria and is not present in eukaryotes, and thus is an excellent target for the innate immune system. Indeed, higher eukaryotes, including mammals, have several PGN recognition molecules, including CD14, Toll-like receptor 2, a family of peptidoglycan recognition proteins, Nod1 and Nod2, and PGN-lytic enzymes (lysozyme and amidases). These molecules induce host responses to microorganisms or have direct antimicrobial effects.Received 15 January 2003; received after revision 28 February 2003; accepted 26 March 2003 相似文献
14.
Pietersz GA Apostolopoulos V McKenzie IF 《Cellular and molecular life sciences : CMLS》2000,57(2):290-310
Tumor immunotherapy is currently receiving close scrutiny. However, with the identification of tumor antigens and their production by recombinant means, the use of cytokines and knowledge of major histocompatibility complex (MHC) class I and class II presentation has provided ample reagents for use and clear indications of how they should be used. At this time, much attention is focused on using peptides to be presented by MHC class I molecules to both induce and be targets for CD8+ cytolytic T cells. Many peptides generated endogenously or given exogenously can enter the class I pathway, but a number of other methods of entering this pathway are also known and are discussed in detail herein. While the review concentrates on inducing cytotoxic T cells (CTLs), it is becoming increasingly apparent that other modes of immunotherapy would be desirable, such as class II presentation to induce increased helper activity (for CTL), but also activating macrophages to be effective against tumor cells. 相似文献
15.
Kristi Baker Timo Rath Wayne I. Lencer Edda Fiebiger Richard S. Blumberg 《Cellular and molecular life sciences : CMLS》2013,70(8):1319-1334
IgG is a molecule that functionally combines facets of both innate and adaptive immunity and therefore bridges both arms of the immune system. On the one hand, IgG is created by adaptive immune cells, but can be generated by B cells independently of T cell help. On the other hand, once secreted, IgG can rapidly deliver antigens into intracellular processing pathways, which enable efficient priming of T cell responses towards epitopes from the cognate antigen initially bound by the IgG. While this process has long been known to participate in CD4+ T cell activation, IgG-mediated delivery of exogenous antigens into a major histocompatibility complex (MHC) class I processing pathway has received less attention. The coordinated engagement of IgG with IgG receptors expressed on the cell-surface (FcγR) and within the endolysosomal system (FcRn) is a highly potent means to deliver antigen into processing pathways that promote cross-presentation of MHC class I and presentation of MHC class II-restricted epitopes within the same dendritic cell. This review focuses on the mechanisms by which IgG-containing immune complexes mediate such cross-presentation and the implications that this understanding has for manipulation of immune-mediated diseases that depend upon or are due to the activities of CD8+ T cells. 相似文献
16.
H. S. Lee Y. S. Kim S. B. Kim B. E. Choi B. H. Woo K. C. Lee 《Cellular and molecular life sciences : CMLS》1999,55(4):679-682
A mistletoe lectin was isolated from water extracts of Korean mistletoe, a subspecies of Viscum album, grown on Quercus mongolica using CM-Sepharose chromatography followed by an affinity chromatography on a concanavalin A-Sepharose column. The compound
proved to be a mistletoe lectin II with D-galactose and N-acetyl-D-galactosamine specificity. Matrix-assisted laser desorption time-of-flight mass spectroscopy showed it to have an
average molecular mass of 62.7 kDa and to consist of two subunits of 30.6 kDa and 32.5 kDa. It was a basic protein with isoelectric
points of 9.4 and 9.6 by capillary isoelectric focusing and was cytotoxic to Molt4 cell.
Received 17 November 1998; received after revision 3 March 1999; accepted 3 March 1999 相似文献
17.
The structure and function of heterotrimeric G protein subunits is known in considerable detail. Upon stimulation of a heptahelical
receptor by the appropriate agonists, the cognate G proteins undergo a cycle of activation and deactivation; the α-subunits and the βγ-dimers interact sequentially with several reaction partners (receptor, guanine nucleotides and effectors as well as regulatory
proteins) by exposing appropriate binding sites. For most of these domains, low molecular weight ligands have been identified
that either activate or inhibit signal transduction. These ligands include short peptides derived from receptors, G protein
subunits and effectors, mastoparan and related insect venoms, modified guanine nucleotides, suramin analogues and amphiphilic
cations. Because compounds that act on G proteins may be endowed with new forms of selectivity, we propose that G protein
subunits may therefore be considered as potential drug targets.
Received 18 September 1998; received after revision 6 November 1998; accepted 11 November 1998 相似文献
18.
M. Karpusas A. Whitty L. Runkel P. Hochman 《Cellular and molecular life sciences : CMLS》1998,54(11):1203-1216
Interferons (IFNs) are potent extracellular protein mediators of host defence and homoeostasis. This article reviews the
structure of human IFN-β (HuIFN-β), in particular in relation to its activity. The recently determined crystal structure of HuIFN-β provides a framework for understanding of the mechanism of differentiation of type I IFNs by their common receptor. Insights
are generated by comparison with the structures of other type I IFNs and from the interpretation of existing mutagenesis data.
The details of the observed carbohydrate structure, together with biochemical data, implicate the glycosylation of HuIFN-β, which is uncommon among type I IFNs, as an important factor in the solubility, stability and, consequently, activity of
the protein. Finally, these structural implications are discussed in the context of the clinical use of HuIFN-β.
Received 12 June 1998; received after revision 16 July 1998; accepted 16 July 1998 相似文献
19.
The neurotrophic factors in non-neuronal tissues 总被引:17,自引:0,他引:17
Sariola H 《Cellular and molecular life sciences : CMLS》2001,58(8):1061-1066
Although neurotrophic factors are defined as molecules that maintain neuronal cells, they possess a range of functions outside
the nervous system. For example, glial cell line-derived neurotrophic factor is essential for ureteric branching in kidney
morphogenesis and for regulating the fate of stem cells during spermatogenesis. Leukemia inhibitory factor, a member of the
interleukin-6 (IL-6) ciliary neurotrophic factor family, inhibits differentiation of embryonic stem cells, induces tubulogenesis
in the embryonic kidney, and regulates sperm differentiation. Other IL-6 family members are important in cardiac differentiation
and they have pleiotropic functions in the hematopoietic and immune systems. Although neurotrophin receptors have been found
on a number of non-neuronal tissues, they represent mostly truncated receptor isoforms that are incapable of signal transduction
and may have scavenger or dominant negative functions. However, several examples can be presented of essential non-neuronal
functions played by neurotrophins in e.g., cardiac, hair follicle, and vascular differentiation, and the maintenance of immune
cells. 相似文献
20.
R. Ippoliti P. Ginobbi E. Lendaro I. D'Agostino D. Ombres P. A. Benedetti M. Brunori G. Citro 《Cellular and molecular life sciences : CMLS》1998,54(8):866-875
The toxicity of two conjugates containing ribosome-inactivating proteins (RIPs, i.e. saporin and ricin-A chain x-linked to
transferrin) has been measured on a prostatic cancer line (PC3) naturally overexpressing the transferrin receptor, in the
presence of monensin and chloroquine. This paper investigates whether the increased toxicity of Tf-RIPs induced by monensin
and chloroquine may be due to alterations of the normal endocytotic pathway of the complexes mediated by the transferrin receptor.
Monensin, besides inducing alkalinization of normally acid intracellular compartments, causes an accumulation of the receptor-bound
Tf-RIP in a perinuclear region contiguous to the cisternae of the trans-Golgi network. Chloroquine, though increasing the
intracellular pH, seems not to modify the endocytotic pathway of these chimeric molecules. We believe that the enhanced toxicity
of the Tf-RIPs may be related to intracellular alkalinization (i.e. endosomal or lysosomal pH) rather than to the effects
on the recycling of transferrin receptor-bound toxins. We conclude that the efficacy of chimeric toxins may be modulated not
only by the carrier used for their engineering but also by addition of drugs able to influence the stability and activation
of the toxins inside the cell.
Received 22 December 1997; received after revision 30 March 1998; accepted 15 May 1998 相似文献