Investigation of Intracellular Signal Transduction on Fetal Brain

我们分析了发育阶段特异性蛋白质在大鼠脑细胞质中的表达，以阐明可能参与中枢神经系统发育的蛋白质。通过制备性电泳从细胞质组分中分离出约30种在产前阶段特异性表达的蛋白质，并进行氨基酸序列分析。尽管已知与生长和分化相关的这些胎儿特异性蛋白质中的几种，如延伸因子-1和HMG-1，已经被表征，但几乎所有其他蛋白质的结构和功能仍然未知。对其中可能与低分子量G蛋白调节因子相关的30 kDA蛋白（p30）和人HLA-DR相关蛋白的大鼠同源物（PHAPI和PHAPII）进行了进一步分析。为了获得编码这些蛋白质的cDNA，以小鼠11天胚胎和小鼠脑cDNA文库为模板，利用根据这些蛋白质的部分氨基酸序列推导的简并寡核苷酸引物进行聚合酶链反应。由于所用的简并引物特异性低，不能成功地克隆p30的cDNA。同时，许多编码PHAPI和PIIAPII的cDNA被克隆，这些cDNA克隆并不完全相同，但彼此密切相关。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.