Retention of cytochrome b5 in the endoplasmic reticulum is transmembrane and luminal domain-dependent

Masanori Honsho, Jun Ya Mitoma, Akio Ito

研究成果: Contribution to journalArticle査読

52 被引用数 (Scopus)

抄録

Cytochrome b5 (b5), a typical tail-anchored protein of the endoplasmic reticulum (ER) membrane, is composed of three functionally different domains: amino-terminal heine-containing catalytic, central hydrophobic membrane- anchoring, and carboxyl-terminal ER-targeting domains (Mitoma, J., and Ito, A. (1992) EMBO J. 11, 41974203). To analyze the potential retention signal of b5, mutant proteins were prepared to replace each domain with natural or artificial sequences, and subcellular localizations were examined using immunofluorescence microscopy and cell fractionation. The transmembrane domain functioned to retain the cytochrome in the ER, and the mutation of all or part of the transmembrane domain with an artificial hydrophobic sequence had practically no effect on intracellular distribution of the cytochrome. However, when the transmembrane domain was extended systematically, a substantial portion of the protein with the domain of over 22 amino acid residues leaked from the organelle. Thus, the transmembrane length functions as the retention signal. When cytochromes with mutations at the carboxyl- terminal end were overexpressed in cells, a substantial portion of the protein was transported to the plasma membrane, indicating that the carboxyl- terminal luminal domain also has a role in retention of b5 in the ER. Carbohydrate moiety of the glycosylatably-mutated b5 was sensitive to endoglycosidase H but resistant to endoglycosidase D. Therefore, both transmembrane and carboxylterminal portions seems to function as the static retention signal.

本文言語英語
ページ(範囲)20860-20866
ページ数7
ジャーナルJournal of Biological Chemistry
273
33
DOI
出版ステータス出版済み - 8 14 1998

All Science Journal Classification (ASJC) codes

  • 生化学
  • 分子生物学
  • 細胞生物学

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