| Project/Area Number |
03680152
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
物質生物化学
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| Research Institution | Kagoshima University |
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Principal Investigator |
OZAWA Masayuki Kagoshima Medicine, University, Associate Professor, 医学部, 助教授 (90136854)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1992: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1991: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Calcium-binding protein / EF-hand / CDNA cloning / ER-resident protein / Glycoprotein / cDNAクロ-ニング |
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| Research Abstract |
A novel Ca^<2+>-binding protein, designated reticulocalbin, has been identified and characterized. Reticulocalbin is a luminal protein of the endoplasmic reticulum with an Mr of 44,000 as revealed by biochemical analysis such as cell fractionation and immunoflurescence staining.
The cDNA of reticulocalbin encodes a protein of 325 amino acids with an amino-terminal signal sequence of 20 amino acids. The protein has six repeats of a domain containing the high affinity Ca^<2+> -binding motif, the EF-hand. Although oxygencontaining amino acids important for the positioning of Ca^<2+> are conserved in all six domains, the conserved glycine reidues in the central portion of the EF-hand motif are absent in three (in sites II, III, and VI) of them. Calcium blots showed that recombinant reticulocalbin expressed in bacterial cells and purified from them binds Ca^<2+>.
The protein has the sequence His-Asp-Glu-Leu (HDEL) at its carboxyl terminus. This sequence is similar to the Lys-Asp-Glu-Leu(KDEL) sequence, which serves as a signal to retain the resident proteins in the endoplasmic reticulum of animal cells. A mutant protein lacking the HDEL sequence produced by in vitro mutagenesis has been shown to be secreted into the medium in transient expression assays.
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