Membrane topology of the 12- and the 25-kDa subunits of the mammalian signal peptidase complex

Item Type:	Article
Title:	Membrane topology of the 12- and the 25-kDa subunits of the mammalian signal peptidase complex
Creators Name:	Kalies, K.U. and Hartmann, E.
Abstract:	The cleavage of signal sequences of secretory and membrane proteins by the signal peptidase complex occurs in the lumen of the endoplasmic reticulum. Mammalian signal peptidase consists of five subunits. Four have been cloned, SPC18, SPC21, SPC22/23, and SPC25, of which all but SPC25 have been demonstrated to be single-spanning membrane proteins exposed to the lumen of the endoplasmic reticulum. We have determined the cDNA sequence of the remaining 12-kDa subunit (SPC12) as well as the membrane topologies of SPC12 and SPC25 in rough microsomes. Both polypeptides span the membrane twice with their N and C termini facing the cytosol and contain only very small, if any, lumenal domains. Therefore, SPC12 and SPC25 are likely to be involved in processes other than the enzymatic cleavage of the signal sequence.
Keywords:	Amino Acid Sequence, Amino Acid Sequence Homology, Base Sequence, Endopeptidases, Intracellular Membranes, Macromolecular Substances, Mammals, Membrane Glycoproteins, Membrane Proteins, Microsomes, Molecular Cloning, Molecular Sequence Data, Molecular Weight, Pancreas, Protein Conformation, Recombinant Proteins, Serine Endopeptidases, Structural Models, Thermodynamics, Animals, Dogs
Source:	Journal of Biological Chemistry
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Volume:	271
Number:	7
Page Range:	3925-3929
Date:	16 February 1996
Official Publication:	https://doi.org/10.1074/jbc.271.7.3925
PubMed:	View item in PubMed

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