Hsp47 and Cyclophilin B Traverse the Endoplasmic Reticulum with Procollagen into Pre-Golgi Intermediate Vesicles

• DOI: 10.1074/jbc.270.31.18323
• Publication Date: 2002-07-26T15:15:23Z
• Authors: Timothy Smith; Luciano R. Ferreira; Carla Hebert; Kathleen Norris; John J. Sauk
• Keywords: Procollagen peptidase; Tunicamycin

Hsp47 and cyclophilin B (CyPB) are residents of the endoplasmic reticulum (ER). Both these proteins closely associated with polysome-associated α1(I) procollagen chains. possesses chaperone properties early during translation while cis/trans-isomerase CyPB facilitate folding. In this report, we further investigate interaction I export from ER. To inhibit vesicular budding retain within ER, cells were treated heterotrimeric G protein inhibitor mastoparan or calphostin C, a specific diacylglycerol/phorbol ester binding proteins. arrest in pre-Golgi intermediate vesicles, guanosine 5ʹ-3-O-(thio)triphosphate. Pulse-chase experiments labeled [35S]methionine followed by immunoprecipitation chase period anti-procollagen, anti-Hsp47, anti-CyPB antibodies performed to reveal relationship between Hsp47/CyPB/procollagen I. The distribution procollagen, Hsp47, ER and/or vesicles was verified immunofluorescence. remained retained also exported into vesicles. Treatment cyclosporin A diminished levels bound rate released secretion, suggesting that release may be driven helix formation. Also, studies suggest resemble disulfide isomerase possess both anti-chaperone properties. During translation, high seen limit aggregation chain registration. Later, act as anti-chaperones provide basis for concentration export.