MOLECULAR-CLONING, CHARACTERIZATION, AND CHROMOSOMAL LOCALIZATION OF FKBP23, A NOVEL FK506-BINDING PROTEIN WITH CA2-BINDING ABILITY()

We have identified and characterized a cDNA encoding a novel FK506-bin ding protein (FKBP), named FKBP23, from mouse heart by the signal sequ ence trap method. The deduced amino acid sequence has significant homo logy to other FKBP family members around the peptidylprolyl cis-trans- isomerase motifs. FKBP23 also has two Ca2+-binding (EF-hand) motifs, a nd purified FKBP23 protein was shown to have Ca2+-binding ability. Thi s is the first report of a Ca2+-binding FKBP. FKBP23 is a glycoprotein retained in the endoplasmic reticulum by its carboxyl-terminal tetrap eptide His-Asp-Glu-Leu, as demonstrated by immunostaining, retention, and deglycosylation assays. FKBP23 mRNA is expressed most strongly in heart, lung, and testis, beginning at day 8.5 of embryonic development . The FKBP23 gene was mapped to mouse chromosome 2. (C) 1998 Academic Press.