Syntaxin 17 is abundant in steroidogenic cells and implicated in smooth endoplasmic reticulum membrane dynamics

• Published in: Molecular biology of the cell Vol. 11; no. 8; pp. 2719 - 2731
• Main Authors: Steegmaier, M, Oorschot, V, Klumperman, J, Scheller, R H
• Format: Journal Article
• Language: English
• Published: United States The American Society for Cell Biology 01.08.2000
• Subjects: Adrenal Cortex - cytology; Adrenal Cortex - metabolism; Adrenal Cortex - ultrastructure; Animals; Carrier Proteins - metabolism; Endoplasmic Reticulum, Smooth - chemistry; Endoplasmic Reticulum, Smooth - metabolism; Endoplasmic Reticulum, Smooth - ultrastructure; Immediate-Early Proteins; Leydig Cells - cytology; Leydig Cells - metabolism; Macromolecular Substances; Male; Membrane Proteins - metabolism; Membrane Proteins - physiology; Membrane Proteins - ultrastructure; Munc18 Proteins; Protein Structure, Tertiary; Qa-SNARE Proteins; Qc-SNARE Proteins; R-SNARE Proteins; Rats; Sequence Deletion; Transfection; Tumor Cells, Cultured; Vesicular Transport Proteins
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.11.8.2719

The endoplasmic reticulum (ER) consists of subcompartments that have distinct protein constituents, morphological appearances, and functions. To understand the mechanisms that regulate the intricate and dynamic organization of the endoplasmic reticulum, it is important to identify and characterize the molecular machinery involved in the assembly and maintenance of the different subcompartments. Here we report that syntaxin 17 is abundantly expressed in steroidogenic cell types and specifically localizes to smooth membranes of the ER. By immunoprecipitation analyses, syntaxin 17 exists in complexes with a syntaxin regulatory protein, rsly1, and/or two intermediate compartment SNARE proteins, rsec22b and rbet1. Furthermore, we found that syntaxin 17 is anchored to the smooth endoplasmic reticulum through an unusual mechanism, requiring two adjacent hydrophobic domains near its carboxyl terminus. Converging lines of evidence indicate that syntaxin 17 functions in a vesicle-trafficking step to the smooth-surfaced tubular ER membranes that are abundant in steroidogenic cells.