Cab45, a novel Ca2+-binding protein localized to the Golgi lumen

Philipp E. Scherer, Gerardo Z. Lederkremer, Suzanne Williams, Michael Fogliano, Giulia Baldini, Harvey F. Lodish

Research output: Contribution to journalArticlepeer-review

129 Scopus citations


We have identified and characterized Cab45, a novel 45-kD protein from mouse 3T3-L1 adipocytes. Cab45 is ubiquitously expressed, contains an NH2-terminal signal sequence but no membrane-anchor sequences, and binds Ca2+ due to the presence of six EF-hand motifs. Within the superfamily of calcium-binding proteins, it belongs to a recently identified group of proteins consisting of Reticulocalbin (Ozawa, M., and T. Muramatsu. 1993. J. Biol. Chem. 268:699-705) and ERC 55 (Weis, K., G. Griffiths, and A.I. Lamond. 1994. J. Biol. Chem. 269:19142-19150), both of which share significant sequence homology with Cab45 outside the EF-hand motifs. In contrast to reticulocalbin and ERC-55 which are soluble components of the endoplasmic reticulum, Cab45 is a soluble protein localized to the Golgi. Cab45 is the first calcium-binding protein localized to the lumenal portion of a post-ER compartment; Cab45 is also the first known soluble protein resident in the Golgi lumen. Cab45 can serve as a model protein to determine the mechanism of retention of soluble proteins in the Golgi compartment.

Original languageEnglish (US)
Pages (from-to)257-268
Number of pages12
JournalJournal of Cell Biology
Issue number2
StatePublished - Apr 1996

ASJC Scopus subject areas

  • Cell Biology


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