| First Author | Fukuda M | Year | 2001 |
| Journal | Biochem J | Volume | 360 |
| Issue | Pt 2 | Pages | 441-8 |
| PubMed ID | 11716773 | Mgi Jnum | J:73334 |
| Mgi Id | MGI:2154894 | Doi | 10.1042/0264-6021:3600441 |
| Citation | Fukuda M, et al. (2001) The N-terminal cysteine cluster is essential for membrane targeting of B/K protein. Biochem J 360(Pt 2):441-8 |
| abstractText | B/K protein belongs to a family of C-terminal-type (C-type) tandem C2 proteins that contain two C2 Ca(2+)-binding motifs at the C-terminus. Although other C-type tandem C2 proteins have been found to have a unique N-terminal domain that is involved in membrane anchoring (e.g. synaptotagmin) or specific ligand binding (e.g. rabphilin-3A and Doc2), no research has been conducted on the function of the N-terminal domain of B/K protein. In this study we showed that despite lacking a transmembrane domain, both native and recombinant B/K proteins are tightly bound to the membrane fraction, which was completely resistant to 0.1 M Na(2)CO(3), pH 11, or 1 M NaCl treatment. Deletion and mutation analyses indicated that the cysteine cluster at the N-terminal domain (consisting of seven cysteine residues, Cys-19, Cys-23, Cys-26, Cys-27, Cys-30, Cys-35 and Cys-36) is essential for the membrane localization of B/K protein. When wild-type B/K was expressed in PC12 cells, B/K proteins were localized mainly in the perinuclear region (trans-Golgi network), whereas mutant B/K proteins carrying Cys-to-Ala substitutions were present in the cytosol. Based on our findings, we propose that the N-terminal domain of B/K protein contains a novel cysteine-based protein motif that may allow B/K protein to localize in the trans-Golgi network. |
