脑表达的X连锁基因的克隆、染色体定位和初步功能研究

通过筛选人18周胎脑cDNA文库，得到一条与Bexl和Bex2在高度同源性的基因，经HUGO／GDB人类基因命名委员会的同意命名为BEX1，Northern杂交发现该基因在脑和胰腺中高表达，在心脏，胎盘，肝脏和肾脏中有较低表达，而在脑和骨骼肌中没有表达，用斯坦福大学G3辐射杂交系将BEX1定位于Xq22上的Marker DXS990和DXS 1059之间，以BEX1作为杂交探针小对小鼠的原位杂交中发现BEX1的小鼠同源基因在小鼠的生精小管中有表达，而在间质组织中没有表达，在成年小鼠（出生10周）中BEX1同源基因在生精小管的外周细胞中表达，在中层细胞（包括次级精母细胞和精子细胞）和内层细胞（主要由精子组成）中没有表达，而在6周的处于青春期的小鼠中，BEX1的同源基因在整个生精小管中都有表达，但外层细胞的表达比中层和内层细胞的表达要高得多，而在3周的幼年小鼠中，BEX1的同源基因仅有微量表达，所以BEX1在小鼠中的同源基因在青春期表达上升，生精小管成熟后表达维持在一定的水平，这提示BEX1基因可能参与精子发生及生精小管发育的过程。

Cloning, Mapping and Characterization of a Novel Human Brain Expressed X-Linked Gene, BEX1

A full length cDNA with 3 479 bp was cloned from a fetal brain cDNA library. It contains an open reading frame encoding a 300 amino acid protein with a calculated molecular mass of 35 379 u and a pI of 5.35. The deduced protein, which was named as RNA binding motif protein 13 (RBM13), shows 41 % identity to MAK16 protein of S. cerevisiae . It contained the signals of a bipartite nuclear localization and an eukaryotic putative RNA binding region RNP 1. Northern blot analysis showed that two sizes of human RBM 13 messenger RNAs (3.6 kb and 2.2 kb) were widely appeared, with highest levels in heart, skeletal muscle, kidney and liver.