共查询到20条相似文献,搜索用时 31 毫秒
1.
G Bailin 《Experientia》1984,40(11):1185-1188
In smooth muscle the Mr 20,000 light chain of myosin is phosphorylated by a calmodulin-dependent protein kinase. It consists of 2 subunits: calmodulin, an acidic protein of Mr 17,000 that binds 4 moles of Ca2+; and a larger protein of Mr circa 130,000. Activation of the kinase is dependent upon their association in the presence of Ca2+. Cyclic AMP-dependent protein kinase phosphorylation of the myosin light chain kinase occurs at 2 sites. It decreases the affinity of the kinase for calmodulin and a reduction in the rate of light chain phosphorylation occurs. The kinase has an overall asymmetric shape composed of a globular head and tail region for the skeletal muscle enzyme. Trypsin digestion of this kinase releases a fragment of Mr 36,000 from the globular region that contains the catalytic and calmodulin binding sites. Chymotrypsin digestion of the kinase from smooth muscle generates a fragment of Mr 80,000 that does not contain the calmodulin binding or cyclic AMP-dependent protein kinase phosphorylation sites. It is a Ca2+-independent form of the kinase that phosphorylates the light chain of myosin. These structural features indicate a regulatory role for the kinase in smooth muscle phosphorylation and contraction. 相似文献
2.
G. Bailin 《Cellular and molecular life sciences : CMLS》1984,40(11):1185-1188
Summary In smooth muscle the Mr 20,000 light chain of myosin is phosphorylated by a calmodulin-dependent protein kinase. It consists of 2 subunits: calmodulin, an acidic protein of Mr 17,000 that binds 4 moles of Ca2+; and a larger protein of Mr circa 130,000. Activation of the kinase is dependent upon their association in the presence of Ca2+. Cyclic AMP-dependent protein kinase phosphorylation of the myosin light chain kinase occurs at 2 sites. It decreases the affinity of the kinase for calmodulin and a reduction in the rate of light chain phosphorylation occurs. The kinase has an overall asymmetric shape composed of a globular head and tail region for the skeletal muscle enzyme. Trypsin digestion of this kinase releases a fragment of Mr 36,000 from the globular region that contains the catalytic and calmodulin binding sites. Chymotrypsin digestion of the kinase from smooth muscle generates a fragment of Mr 80,000 that does not contain the calmodulin binding or cyclic AMP-dependent protein kinase phosphorylation sites. It is a Ca2+-independent form of the kinase that phosphorylates the light chain of myosin. These structural features indicate a regulatory role for the kinase in smooth muscle phosphorylation and contraction. 相似文献
3.
Sjöblom B Salmazo A Djinović-Carugo K 《Cellular and molecular life sciences : CMLS》2008,65(17):2688-2701
Alpha-actinin is a cytoskeletal actin-binding protein and a member of the spectrin superfamily, which comprises spectrin, dystrophin and their homologues and isoforms. It forms an anti-parallel rod-shaped dimer with one actin-binding domain at each end of the rod and bundles actin filaments in multiple cell-type and cytoskeleton frameworks. In non-muscle cells, alpha-actinin is found along the actin filaments and in adhesion sites. In striated, cardiac and smooth muscle cells, it is localized at the Z-disk and analogous dense bodies, where it forms a lattice-like structure and stabilizes the muscle contractile apparatus. Besides binding to actin filaments alpha-actinin associates with a number of cytoskeletal and signaling molecules, cytoplasmic domains of transmembrane receptors and ion channels, rendering it important structural and regulatory roles in cytoskeleton organization and muscle contraction. This review reports on the current knowledge on structure and regulation of alpha-actinin. 相似文献
4.
Giel Tanghe Corinne Urwyler-Rösselet Philippe De Groote Emmanuel Dejardin Pieter-Jan De Bock Kris Gevaert Peter Vandenabeele Wim Declercq 《Cellular and molecular life sciences : CMLS》2018,75(15):2827-2841
RIPK4 is a key player in epidermal differentiation and barrier formation. RIPK4 signaling pathways controlling keratinocyte proliferation and differentiation depend on its kinase activity leading to Dvl2, Pkp1 and IRF6 phosphorylation and NF-κB activation. However, the mechanism regulating RIPK4 activity levels remains elusive. We show that cultured keratinocytes display constitutive active phosphorylated RIPK4 while PKC signaling can trigger RIPK4 activation in various non-keratinocyte cell lines, in which RIPK4 is present in a non-phosphorylated state. Interestingly, we identified the SCFβ-TrCP ubiquitin E3 ligase complex responsible for regulating the active RIPK4 protein level. The SCFβ-TrCP complex binds to a conserved phosphodegron motif in the intermediate domain of RIPK4, subsequently leading to K48-linked ubiquitinylation and degradation. The recruitment of β-TrCP is dependent on RIPK4 activation and trans-autophosphorylation. β-TrCP knock-down resulted in RIPK4-dependent formation of actin stress fibers, cell scattering and increased cell motility, suggesting that tight control of RIPK4 activity levels is crucial to maintain cell shape and behavior in keratinocytes. 相似文献
5.
Protein kinase C (PKC) is an important signaling molecule in the heart, but its targets remain unclear. Using a PKC substrate
antibody, we detected a 40-kDa phosphorylated cardiac protein that was subsequently identified by tandem mass spectroscopy
as muscle creatine kinase (M-CK) with phosphorylation at serine 128. The forward reaction using ATP to generate phosphocreatine
was reduced, while the reverse reaction using phosphocreatine to generate ATP was increased following dephosphorylation of
immunoprecipitated M-CK with protein phosphatase 2A (PP2A) or PP2C. Despite higher PKC levels in diabetic hearts, decreased
phosphorylation of M-CK was more prominent than the reduction in its expression. Changes in CK activity in diabetic hearts
were similar to those found following dephosphorylation of M-CK from control hearts. The decrease in phosphorylation may act
as a compensatory mechanism to maintain CK activity at an appropriate level for cytosolic ATP regeneration in the diabetic
heart.
Received 15 September 2008; received after revision 30 September 2008; accepted 13 October 2008 相似文献
6.
Yun Hyun Huh So Hee Kim Kyoung-Hwun Chung Sena Oh Min-Sung Kwon Hyun-Woo Choi Sangmyung Rhee Je-Hwang Ryu Zee Yong Park Chang-Duk Jun Woo Keun Song 《Cellular and molecular life sciences : CMLS》2013,70(24):4841-4854
Membrane protrusions, like lamellipodia, and cell movement are dependent on actin dynamics, which are regulated by a variety of actin-binding proteins acting cooperatively to reorganize actin filaments. Here, we provide evidence that Swiprosin-1, a newly identified actin-binding protein, modulates lamellipodial dynamics by regulating the accessibility of F-actin to cofilin. Overexpression of Swiprosin-1 increased lamellipodia formation in B16F10 melanoma cells, whereas knockdown of Swiprosin-1 inhibited EGF-induced lamellipodia formation, and led to a loss of actin stress fibers at the leading edges of cells but not in the cell cortex. Swiprosin-1 strongly facilitated the formation of entangled or clustered F-actin, which remodeled the structural organization of actin filaments making them inaccessible to cofilin. EGF-induced phosphorylation of Swiprosin-1 at Ser183, a phosphorylation site newly identified using mass spectrometry, effectively inhibited clustering of actin filaments and permitted cofilin access to F-actin, resulting in actin depolymerization. Cells overexpressing a Swiprosin-1 phosphorylation-mimicking mutant or a phosphorylation-deficient mutant exhibited irregular membrane dynamics during the protrusion and retraction cycles of lamellipodia. Taken together, these findings suggest that dynamic exchange of Swiprosin-1 phosphorylation and dephosphorylation is a novel mechanism that regulates actin dynamics by modulating the pattern of cofilin activity at the leading edges of cells. 相似文献
7.
Myosin V from head to tail 总被引:1,自引:1,他引:0
Trybus KM 《Cellular and molecular life sciences : CMLS》2008,65(9):1378-1389
Myosin V (myoV), a processive cargo transporter, has arguably been the most well-studied unconventional myosin of the past
decade. Considerable structural information is available for the motor domain, the IQ motifs with bound calmodulin or light
chains, and the cargo-binding globular tail, all of which have been crystallized. The repertoire of adapter proteins that
link myoV to a particular cargo is becoming better understood, enabling cellular transport processes to be dissected. MyoV
is processive, meaning that it takes many steps on actin filaments without dissociating. Its extended lever arm results in
long 36-nm steps, making it ideal for single molecule studies of processive movement. In addition, electron microscopy revealed
the structure of the inactive, folded conformation of myoV when it is not transporting cargo. This review provides a background
on myoV, and highlights recent discoveries that show why myoV will continue to be an active focus of investigation.
Received 31 October 2007; received after revision 4 December 2007; accepted 2 January 2008 相似文献
8.
The isoform-specific regulation of apoptosis by protein kinase C 总被引:18,自引:0,他引:18
The process of apoptosis is regulated at several levels through phosphorylation by many different protein kinases. The protein kinase C (PKC) family, which comprises at least 10 isoforms with distinct means of regulation and tissue distribution patterns, have been shown to exert both inhibitory and stimulatory influences on apoptosis. This review details recent progress made in determining the roles played by individual PKC isoforms in the control of apoptosis, with reference to their target substrates and actions in different cell types. Although notable exceptions exist, the weight of evidence indicates that the alpha, beta, epsilon and atypical isoforms are anti-apoptotic in their action, whereas the delta and theta isoforms are usually involved in the promotion of apoptosis. 相似文献
9.
Trueb B 《Cellular and molecular life sciences : CMLS》2011,68(6):951-964
FGFRL1 (fibroblast growth factor receptor like 1) is the most recently discovered member of the FGFR family. It contains three
extracellular Ig-like domains similar to the classical FGFRs, but it lacks the protein tyrosine kinase domain and instead
contains a short intracellular tail with a peculiar histidine-rich motif. The gene for FGFRL1 is found in all metazoans from
sea anemone to mammals. FGFRL1 binds to FGF ligands and heparin with high affinity. It exerts a negative effect on cell proliferation,
but a positive effect on cell differentiation. Mice with a targeted deletion of the Fgfrl1 gene die perinatally due to alterations
in their diaphragm. These mice also show bilateral kidney agenesis, suggesting an essential role for Fgfrl1 in kidney development.
A human patient with a frameshift mutation exhibits craniosynostosis, arguing for an additional role of FGFRL1 during bone
formation. FGFRL1 contributes to the complexity of the FGF signaling system. 相似文献
10.
Wnt-frizzled signaling to G-protein-coupled effectors 总被引:2,自引:0,他引:2
11.
Engen JR Wales TE Hochrein JM Meyn MA Banu Ozkan S Bahar I Smithgall TE 《Cellular and molecular life sciences : CMLS》2008,65(19):3058-3073
Src-family kinases are modular signaling proteins involved in a diverse array of cellular processes. All members of the Src
family share the same domain organization, with modular SH3, SH2 and kinase domains followed by a C-terminal negative regulatory
tail. X-ray crystallographic analyses of several Src family members have revealed critical roles for the SH3 and SH2 domains
in the down-regulation of the kinase domain. This review focuses on biological, biophysical, and computational studies that
reveal conformationally distinct active states within this unique kinase family.
Received 10 March 2008; received after revision 17 May 2008; accepted 21 May 2008 相似文献
12.
Christian M. Udell Thanashan Rajakulendran Frank Sicheri Marc Therrien 《Cellular and molecular life sciences : CMLS》2011,68(4):553-565
The RAF family of kinases are key components acting downstream of receptor tyrosine kinases and cells employ several distinct
mechanisms to strictly control their activity. RAF transitions from an inactive state, where the N-terminal regulatory region
binds intramolecularly to the C-terminal kinase domain, to an open state capable of executing the phosphoryl transfer reaction.
This transition involves changes both within and between the protein domains in RAF. Many different proteins regulate the
transition between inactive and active states of RAF, including RAS and KSR, which are arguably the two most prominent regulators
of RAF function. Recent developments have added several new twists to our understanding of RAF regulation. Among others, dimerization
of the RAF kinase domain is emerging as a crucial step in the RAF activation process. The multitude of regulatory protein–protein
interactions involving RAF remains a largely untapped area for therapeutic applications. 相似文献
13.
Lu W Schneider M Neumann S Jaeger VM Taranum S Munck M Cartwright S Richardson C Carthew J Noh K Goldberg M Noegel AA Karakesisoglou I 《Cellular and molecular life sciences : CMLS》2012,69(20):3493-3509
Nesprins-1/-2/-3/-4 are nuclear envelope proteins, which connect nuclei to the cytoskeleton. The largest nesprin-1/-2 isoforms (termed giant) tether F-actin through their N-terminal actin binding domain (ABD). Nesprin-3, however, lacks an ABD and associates instead to plectin, which binds intermediate filaments. Nesprins are integrated into the outer nuclear membrane via their C-terminal KASH-domain. Here, we show that nesprin-1/-2 ABDs physically and functionally interact with nesprin-3. Thus, both ends of nesprin-1/-2 giant are integrated at the nuclear surface: via the C-terminal KASH-domain and the N-terminal ABD-nesprin-3 association. Interestingly, nesprin-2 ABD or KASH-domain overexpression leads to increased nuclear areas. Conversely, nesprin-2 mini (contains the ABD and KASH-domain but lacks the massive nesprin-2 giant rod segment) expression yields smaller nuclei. Nuclear shrinkage is further enhanced upon nesprin-3 co-expression or microfilament depolymerization. Our findings suggest that multivariate intermolecular nesprin interactions with the cytoskeleton form a lattice-like filamentous network covering the outer nuclear membrane, which determines nuclear size. 相似文献
14.
15.
Jung-Eun Park Nak-Kyun Soung Yoshikazu Johmura Young H. Kang Chenzhong Liao Kyung H. Lee Chi Hoon Park Marc C. Nicklaus Kyung S. Lee 《Cellular and molecular life sciences : CMLS》2010,67(12):1957-1970
Members of the polo subfamily of protein kinases have emerged as important regulators in diverse aspects of the cell cycle
and cell proliferation. A large body of evidence suggests that a highly conserved polo-box domain (PBD) present in the C-terminal
non-catalytic region of polo kinases plays a pivotal role in the function of these enzymes. Recent advances in our comprehension
of the mechanisms underlying mammalian polo-like kinase 1 (Plk1)-dependent protein–protein interactions revealed that the
PBD serves as an essential molecular mediator that brings the kinase domain of Plk1 into proximity with its substrates, mainly
through phospho-dependent interactions with its target proteins. In this review, current understanding of the structure and
functions of PBD, mode of PBD-dependent interactions and substrate phosphorylation, and other phospho-independent functions
of PBD are discussed. 相似文献
16.
M. G. Monti G. Marverti S. Ghiaroni G. Piccinini L. Pernecco M. S. Moruzzi 《Cellular and molecular life sciences : CMLS》1994,50(10):953-957
Phosphatidylserine (PS), an activator of protein kinase C (PKC) in the assay of protein phosphorylation, inhibited this enzyme in a time-dependent manner following preincubation in the absence of Ca2+. The phospholipid-induced inactivation of kinase activity was dependent on the PS content and on the charge density of liposomes. This inactivation of PKC could be reduced, but not completely eliminated, by addition of Ca2+. In the present work the effect of a naturally occurring polyamine (spermine) on the PS-induced inactivation of PKC was investigated. The presence of spermine during preincubation without Ca2+ was effective in suppressing the PS-induced inactivation of PKC over the period (20 min) required for PS to inhibit the enzyme by 95%. PKC exists in two membrane-bound states: a reversible one which can be dissociated by Ca2+ chelators (membrane-associated form) and an irreversible one which is chelator-stable (membrane-inserted form). Gel filtration experiments on the PKC-PS complex formed in the presence of Ca2+ indicated that less insertion of enzyme into liposomes occurred in the presence of spermine and that the kinase activity of the reversibly membrane-associated PKC was protected from PS inactivation. 相似文献
17.
Kostyukova AS 《Cellular and molecular life sciences : CMLS》2008,65(4):563-569
The tropomodulins are a family of proteins that cap the slow-growing (pointed) end of actin filaments and require tropomyosin
for optimal function. Tropomodulin is an elongated molecule with a molecular mass of about 40 kDa. The C-terminal half of
tropomodulin contains one compact cooperatively melting domain, whereas the N-terminal half has no cooperatively melting structure.
The N-terminal half of tropomodulin contains two tropomysin-binding sites and a tropomyosin-dependent actin-binding site,
the tropomyosin-independent actin-binding site being located at the C terminus. One tropomodulin molecule binds two tropomyosin
molecules, and thus one molecule of tropomodulin is necessary and sufficient for capping at the pointed end. Tropomyosin/tropomodulin
interactions are isoform specific. Differences in tropomyosin affinity for the two binding sites in tropomodulin may regulate
its correct positioning at the pointed end as well as effectiveness of capping the actin filament.
Received 30 July 2007; received after revision 2 October 2007; accepted 10 October 2007 相似文献
18.
Alemu EA Sjøttem E Outzen H Larsen KB Holm T Bjørkøy G Johansen T 《Cellular and molecular life sciences : CMLS》2011,68(11):1953-1968
The protein kinase C (PKC) family of serine/threonine kinases consists of ten different isoforms grouped into three subfamilies,
denoted classical, novel and atypical PKCs (aPKCs). The aPKCs, PKCι/λ and PKCζ serve important roles during development and
in processes subverted in cancer such as cell and tissue polarity, cell proliferation, differentiation and apoptosis. In an
effort to identify novel interaction partners for aPKCs, we performed a yeast two-hybrid screen with the regulatory domain
of PKCι/λ as bait and identified the Krüppel-like factors family protein TIEG1 as a putative interaction partner for PKCι/λ.
We confirmed the interaction of both aPKCs with TIEG1 in vitro and in cells, and found that both aPKCs phosphorylate the DNA-binding
domain of TIEG1 on two critical residues. Interestingly, the aPKC-mediated phosphorylation of TIEG1 affected its DNA-binding
activity, subnuclear localization and transactivation potential. 相似文献
19.
M. Renucci A. Tirard L. Sreng J. Khlat J. L. Clément 《Cellular and molecular life sciences : CMLS》1996,52(8):762-768
In insect antennal extracts, Schleicher et al.1 showed that protein kinase C (PKC) inhibitors abolish the transience of pheromone-induced rapid inositol trisphosphate responses, which suggests that pheromonal signals act on phosphorylation of specific proteins. To confirm this hypothesis, we studied the effects of second messengers and a pheromonal blend on phosphorylation of antennal proteins in the cockroachPeriplaneta americana. Proteins from adult male antennae were phosphorylated in vitro in the presence of [32P] triphosphate, then separated by SDS-polyacrylamide gel electrophoresis. Numerous phosphopolypeptides were visualized. The presence of Ca++/calmodulin in the incubation medium resulted in increased phosphorylation of polypeptides with molecular weights of 38, 48, 51, 54 and 58 kDa. Stimulation of PKC by addition of Ca++ phosphatidylserine (PS)/phorbol myristate acetate (PMA) resulted in the appearance of three phosphopolypeptides of 36, 70 and 120 kDa. In the presence of cyclic adenosine monophosphate, two new major polypeptides of 46 and 42 kDa appeared; the latter polypeptide also appeared in the presence of cyclic guanosine monophosphate. Comparison with polypeptide composition of tissue from the cerci, leg, brain and fat body showed that the 36 and 48 kDa polypeptides were specific to antennae, whereas the 120 kDa polypeptide was also present in the adult brain. When antennae are subjected to pheromonal stimulation for 16 seconds prior to homogenization, in vitro phosphorylation of the 120, 70, 64 and 38 kDa polypeptides was inhibited, whereas phosphorylation of the 58, 54, 51 and 48 kDa polypeptides was strongly stimulated. It is noteworthy that a 107 kDa polypeptide was observed only after pheromonal stimulation by Ca++/PS/PMA. Our findings suggest that Ca++-and PKC-dependent protein phosphorylation systems play an important role in the transduction of pheromonal signals in antennae of male cockroachP. americana. We speculate that specific phosphoproteins may modulate sensitivity and signal amplification during the olfactory transduction process. 相似文献
20.
Sarah De Clercq Olivier Zwaenepoel Evelien Martens Joël Vandekerckhove Aude Guillabert Jan Gettemans 《Cellular and molecular life sciences : CMLS》2013,70(5):909-922
The T cell integrin receptor LFA-1 orchestrates adhesion between T cells and antigen-presenting cells (APCs), resulting in formation of a contact zone known as the immune synapse (IS) which is supported by the cytoskeleton. L-plastin is a leukocyte-specific actin bundling protein that rapidly redistributes to the immune synapse following T cell–APC engagement. We used single domain antibodies (nanobodies, derived from camelid heavy-chain only antibodies) directed against functional and structural modules of L-plastin to investigate its contribution to formation of an immune synapse between Raji cells and human peripheral blood mononuclear cells or Jurkat T cells. Nanobodies that interact either with the EF hands or the actin binding domains of L-plastin both trapped L-plastin in an inactive conformation, causing perturbation of IS formation, MTOC docking towards the plasma membrane, T cell proliferation and IL-2 secretion. Both nanobodies delayed Ser5 phosphorylation of L-plastin which is required for enhanced bundling activity. Moreover, one nanobody delayed LFA-1 phosphorylation, reduced the association between LFA-1 and L-plastin and prevented LFA-1 enrichment at the IS. Our findings reveal subtle mechanistic details that are difficult to attain by conventional means and show that L-plastin contributes to immune synapse formation at distinct echelons. 相似文献