Ribonucleoparticle-independent import of proteins into mammalian microsomes involves a membrane protein which is sensitive to chemical alkylation.
Import of the small precursor protein preprocecropin A (ppcec A) into dog pancreas microsomes under post-translational conditions does not involve the ribonucleoparticles, signal recognition particle and ribosome, and their receptors on the microsomal surface, docking protein and ribosome receptor. In this study, we attempted to obtain direct evidence for the involvement of proteinaceous membrane components in this alternative import mechanism by utilizing various sulfhydryl-modifying reagents (N-ethylmaleimide (NEM), N-iodoacetylaminoethyl-5-naphthylamine-1- sulphonic acid (AEDANS) and iodoacetamide (IAA]. As a result of observing the inhibitory effect of 2 reagents (NEM and AEDANS) on the microsomes with respect to ppcec A-import, we concluded that there is at least one membrane protein with a cytoplasmically exposed sulfhydryl involved in ppcep A-import. This membrane protein(s) is (are) distinct from membrane proteins which are known to be involved in protein import, such as the signal peptidase and the so-called signal sequence receptor.
Zimmermann
R
R
Institut für Physiologische Chemie der Universität München, FRG.
Sagstetter
M
M
Schlenstedt
G
G
D000477:Alkylating Agents / Q000494:pharmacology; D000478:Alkylation; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004285:Dogs; D007301:Insect Hormones / Q000378:metabolism*; D019476:Insect Proteins; D008565:Membrane Proteins / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism*; D010179:Pancreas / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D000477:Alkylating Agents; C059037:CecA2 protein, Bombyx mori; D007301:Insect Hormones; D019476:Insect Proteins; D008565:Membrane Proteins; D011498:Protein Precursors; D013439:Sulfhydryl Reagents