Feinstein D L, Weinmaster G A, Milner R J
Department of Neuropharmacology, Scripps Research Institute, La Jolla, California.
J Neurosci Res. 1992 May;32(1):1-14. doi: 10.1002/jnr.490320102.
Glial fibrillary acidic protein (GFAP) expressed by astrocytes in the central nervous system (CNS) has been extensively characterized but the molecular identity of related molecules in the peripheral nervous system (PNS) remains unclear. To examine possible structural differences between CNS and PNS GFAP, we have isolated cDNA clones for rat GFAP from both cultured astrocyte and Schwann cell libraries. Nucleotide sequence analysis indicated that the PNS and CNS GFAP clones contained identical coding regions, with a predicted protein product of 430 amino acids. However, the 5'-untranslated region of clone rGFA15, isolated from the Schwann cell library, was longer than that predicted for brain-derived GFAP mRNA. Primer extension analysis of RNA isolated from the RT4-D6 Schwann cell line indicated that the start site for PNS GFAP mRNA lies 169 bases upstream from that used in the CNS. In addition, tryptic peptide mapping of GFAP prepared from cultured astrocytes and Schwann cells revealed one major peptide fragment present in CNS GFAP but absent from PNS GFAP. These results suggest structural differences between GFAP in these two cell types, at both the nucleic acid and protein level, and are consistent with previous observations of immunochemical differences existing between CNS and PNS GFAP.
中枢神经系统（CNS）中星形胶质细胞表达的胶质纤维酸性蛋白（GFAP）已得到广泛研究，但外周神经系统（PNS）中相关分子的分子特性仍不清楚。为了研究CNS和PNS中GFAP可能存在的结构差异，我们从培养的星形胶质细胞文库和雪旺氏细胞文库中分离出大鼠GFAP的cDNA克隆。核苷酸序列分析表明，PNS和CNS的GFAP克隆含有相同的编码区，预测的蛋白质产物为430个氨基酸。然而，从雪旺氏细胞文库中分离出的克隆rGFA15的5'-非翻译区比脑源性GFAP mRNA预测的更长。对从RT4-D6雪旺氏细胞系分离的RNA进行引物延伸分析表明，PNS中GFAP mRNA的起始位点比CNS中使用的起始位点上游169个碱基。此外，对培养的星形胶质细胞和雪旺氏细胞制备的GFAP进行胰蛋白酶肽图谱分析发现，CNS中存在一个主要的肽片段，而PNS中不存在。这些结果表明这两种细胞类型中的GFAP在核酸和蛋白质水平上均存在结构差异，并且与之前观察到的CNS和PNS中GFAP存在免疫化学差异一致。
