SUMMARY PARAGRAPH for SPC1
SPC1 encodes a subunit of the signal peptidase complex (SPC), which cleaves the signal sequence from proteins targeted to the endoplasmic reticulum (ER) (1). Signal peptide cleavage occurs concomitantly with translocation through the translocon pore into the ER. In yeast, translocation can occur cotranslationally or posttranslationally, whereas in mammals translocation is always cotranslational. The process of protein translocation into the ER is reviewed in references 4 and 5.
The yeast SPC comprises four proteins, Spc1p, Spc2p, Spc3p, and Sec11p (6, 2). Spc1p is homologous to the mammalian signal peptidase subunit SPC12 (1). Spc1p is not essential for viability or for signal peptidase activity in vivo or in vitro (1, 2), and cells lacking both Spc1p and Spc2p are also viable (7). Deletion of SPC1 is synthetically lethal with a temperature-sensitive mutation in SEC11, which encodes the catalytic SPC subunit (7). Overexpression of SPC1 suppresses the sec11 temperature sensitive phenotype (1).
Last updated: 2000-11-27