| Research Abstract |
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.
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