Physiological and structural studies of evolutionaly conserved-perchloric acid soluble-protein )PSP) from rat liver

我们从大鼠脑线粒体后上清中分离出一种高氯酸可溶性蛋白B-PSP1。经凝胶过滤和抗psp亲和层析纯化。免疫印迹、多肽定位、部分氨基酸测序和逆转录聚合酶链反应表明，B-PSP1的氨基酸序列与从大鼠肝脏分离的PSP相同。B-PSP1在额皮质、后皮质、小脑、海马、嗅球、纹状体、丘脑、中脑、室管膜皮质、脑桥、髓质和脊髓等所有区域均有表达。免疫组化研究显示，B-PSP1在脉络膜丛室管膜细胞和其他区域的胶质细胞中均有表达。出生后第1天至第60天，B-PSP1在脑内的表达逐渐增加，但其表达速度慢于胶质细胞标记蛋白GFAP。PSP的表达可能与细胞功能有关，而不是与胶质细胞的发育调节有关。另一方面，在正常大鼠肾上皮NRK-52E细胞中检测K-PSP1的表达。K-PSP1在增殖期低表达，在静止期高表达，且与细胞的蛋白合成活性呈负相关。此外，转染PCDNA-sense-PSP的细胞过表达PSP mRNA及其蛋白，与转染PCDNA-empty的细胞相比，转染后的细胞增殖受到抑制。

We have isolated a perchloric acid-soluble protein designated as B-PSP1 from the postmitochondria supernatant fraction of rat brain. It was purified by gel filtration and anti-PSP affinity chromatography. Immunoblotting, peptide mapping, partial amino acid sequencing and reverse transcriptaspolymerase chain reaction shwed the amino acid sequence of B-PSP1 was identical with that of PSP isolated from rat liver. B-PSP1 was expressed in all regions including frontal cortex, posterior cortex, cerebellum, hippocampus, olfactory bulb, striatum, thalamus, midbrain, ependymal cortex, pons, medulla and spinal cord. Immunohistochemical study showed that the expression of B-PSP1 was observed in ependymal cells of choroid plexus and glial cells of the other region. The expression of B-PSP1 in brain increased gradually from the first day to the 60th day of postnatal age, but the expression of B-PSP1 was slower than that of GFAP which is a marker protein of glial cells. The expression of PSP may be related to the cellular function rather than the developmental regulation of the glial cells.On the other hand, the expression of K-PSP1 was examined in normal rat kidney epithelial NRK-52E cells. The expression of K-PSP1 was low during the proliferating phase and high in the stationary phase, and shown to have a negative relationship with the protein-synthesizing activity of the cells. Furthermore, the cells transfected PCDNA-sense-PSP overexpressed the PSP mRNA and its protein, and the cell proliferation of the transfected cells was suppressed conmapared with that of the cells transfected with PCDNA-empty.