Investigation of Intracellular Signal Transduction on Fetal Brain

我们分析了大鼠脑细胞质中发育阶段特异性蛋白的表达，以阐明可能参与中枢神经系统发育的蛋白。通过制备电泳，从胞浆中分离出约30个在产前特异性表达的蛋白，并进行氨基酸序列分析。虽然已知与生长和分化有关的一些胎儿特异性蛋白，如伸长因子-1和HMG-1，已经被鉴定，但几乎所有其他蛋白质的结构和功能仍然未知。在这些蛋白中，进一步分析了可能与低分子量G蛋白调控因子相关的30kda蛋白（p30）和人类推定的HLA-DR相关蛋白（PHAPI和PHAPII）的大鼠同源物。以小鼠11天胚和小鼠脑cDNA文库为模板，利用这些蛋白的部分氨基酸序列推导出退化的寡核苷酸引物，进行多聚酶链反应，获得编码这些蛋白的cDNA。由于所使用的退化引物特异性较低，编码p30的cDNA克隆不成功。而编码PHAPI和PIIAPII的cDNA克隆很多，这些cDNA克隆并不完全相同，但彼此关系密切。核苷酸序列与推导出的氨基酸序列的比较表明，PIJAPI和P11 APII都有许多由选择性剪接产生的分子片段。

We analyzed developmental stage-specific protein expression in rat brain cytosol to clarify proteins which might be involved in the development of the central nervous system. About 30 proteins that are expressed specifically at the prenatal stage were isolated from the cytosol fraction by preparative electrophoresis and were subjected to amino acid sequence analysis. Although several of these fetal specific proteins, such as elongation factor-1 and HMG-1, which arc known to be related to growth and differentiation have been characterized, the structure and function of almost all other proteins are still unknown. Among these proteins, 30 kDA protein (p30) which might be related to regulatory factor of low molecular weight G protein and rat homologues of human putative HLA-DR associated proteins (PHAPI and PHAPII) were further analyzed. To obtain the cDNA encoding these proteins, polynierase chain reaction was performed using mouse 11-day embryo and mouse brain cDNA library as template and degenerated oligonucleotide primers deduced from partial amino acid sequences of these proteins. Since the specificity of used degenerated primers were low, cloning of the cDNA encoding p30 aws not successful. While, many cDNA encoding PHAPI and PIIAPII were cloned and these cDNA clones were not identical, but closely related each other. Comparison of nuelcotidesequences and deduced amino acid sequences suggest that both PIJAPI and P11 APII have many molecular spieces generated by alternative splicing.