title: GERp95, a membrane-associated protein that belongs to a family of proteins involved in stem cell differentiation.
abstract: A panel of mAbs was elicited against intracellular membrane fractions from rat pancreas. One of the antibodies reacted with a 95-kDa protein that localizes primarily to the Golgi complex or the endoplasmic reticulum (ER), depending on cell type. The corresponding cDNA was cloned and sequenced and found to encode a protein of 97.6 kDa that we call GERp95 (Golgi ER protein 95 kDa). The protein copurifies with intracellular membranes but does not contain hydrophobic regions that could function as signal peptides or transmembrane domains. Biochemical analysis suggests that GERp95 is a cytoplasmically exposed peripheral membrane protein that exists in a protease-resistant complex. GERp95 belongs to a family of highly conserved proteins in metazoans and Schizosaccharomyces pombe. It has recently been determined that plant and Drosophila homologues of GERp95 are important for controlling the differentiation of stem cells (Bohmert et al., 1998; Cox et al., 1998; Moussian et al., 1998). In Caenorhabditis elegans, there are at least 20 members of this protein family. To this end, we have used RNA interference to show that the GERp95 orthologue in C. elegans is important for maturation of germ-line stem cells in the gonad. GERp95 and related proteins are an emerging new family of proteins that have important roles in metazoan development. The present study suggests that these proteins may exert their effects on cell differentiation from the level of intracellular membranes.
authors.affiliation: Department of Cell Biology, University of Alberta, Edmonton, AB, T6G 2H7, Canada.
authors.forename: D E
authors.initials: DE
authors.lastname: Cikaluk
authors.forename: N
authors.initials: N
authors.lastname: Tahbaz
authors.forename: L C
authors.initials: LC
authors.lastname: Hendricks
authors.forename: G E
authors.initials: GE
authors.lastname: DiMattia
authors.forename: D
authors.initials: D
authors.lastname: Hansen
authors.forename: D
authors.initials: D
authors.lastname: Pilgrim
authors.forename: T C
authors.initials: TC
authors.lastname: Hobman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D060565:Argonaute Proteins; D019556:COS Cells; D017173:Caenorhabditis elegans / Q000378:metabolism; D002454:Cell Differentiation; D003001:Cloning, Molecular; D004721:Endoplasmic Reticulum / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2; D005455:Fluorescent Antibody Technique; D005854:Germ Cells / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007425:Intracellular Membranes / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010179:Pancreas / Q000737:chemistry*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins; D012098:Reproduction; D016415:Sequence Alignment; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D014162:Transfection
chemical_list: C582332:Ago2 protein, rat; D060565:Argonaute Proteins; D015852:Eukaryotic Initiation Factor-2; D008565:Membrane Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins