Investigation of Intracellular Signal Transduction on Fetal Brain

我们分析了发育阶段特异的蛋白质在大鼠脑胞浆中的表达，以阐明可能参与中枢神经系统发育的蛋白质。用制备电泳法从胞浆组分中分离出约30个在胎儿期特异表达的蛋白质，并进行氨基酸序列分析。虽然已经鉴定了其中几个与生长和分化相关的胎儿特异性蛋白，如延伸因子-1和HMG-1，但几乎所有其他蛋白的结构和功能仍不清楚。在这些蛋白质中，进一步分析了可能与低分子量G蛋白调节因子有关的30个KDA蛋白(P30)和大鼠可能的人类HLA-DR相关蛋白的同源物(PHAPI和PHAPII)。为获得这些蛋白的编码基因，以小鼠11日龄胚胎和小鼠脑cDNA文库为模板，根据这些蛋白的部分氨基酸序列设计简并的寡核苷酸引物，进行聚合酶链式反应。由于所用简并引物的特异性较低，因此P30基因的克隆不成功。同时，还克隆了许多编码PHAPI和PIIAPII的基因，这些克隆虽然不完全相同，但却密切相关。核苷酸序列和推导的氨基酸序列的比较表明，PIJAPI和P11ApiI都有许多通过选择性剪接产生的分子特异体。

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.