Nakai M, Nohara T, Sugita D, Endo T
Department of Chemistry, Faculty of Science, Nagoya University, Japan.
Biochem Biophys Res Commun. 1994 Apr 29;200(2):844-51. doi: 10.1006/bbrc.1994.1528.
The secA gene product mediates protein translocation across the cytoplasmic membrane in Escherichia coli. We have cloned a gene homologous to secA from the genome of the cyanobacterium Synechococcus PCC7942. The deduced amino acid sequence, 948 amino acids long, shows 43% homology with that of the E. coli secA and 47-48% homology with those of the algal plastid secA genes. Upon subcellular fractionation, the cyanobacterial SecA protein was mainly found as soluble homodimer in the cytosol, but the remaining small but distinct fraction was associated with both the cytoplasmic and thylakoid membranes. The SecA protein likely participates in protein translocation across both the cytoplasmic and thylakoid membranes in cyanobacterial cells.
secA基因产物介导大肠杆菌中蛋白质穿过细胞质膜的转运。我们从蓝藻聚球藻PCC7942的基因组中克隆了一个与secA同源的基因。推导的氨基酸序列长948个氨基酸，与大肠杆菌secA的氨基酸序列有43%的同源性，与藻类质体secA基因的氨基酸序列有47%-48%的同源性。亚细胞分级分离后，蓝藻SecA蛋白主要以可溶性同型二聚体的形式存在于胞质溶胶中，但其余少量但明显的部分与细胞质膜和类囊体膜都有关联。SecA蛋白可能参与蓝藻细胞中蛋白质穿过细胞质膜和类囊体膜的转运。
