| First Author | Kroczynska B | Year | 2005 |
| Journal | Biochem Biophys Res Commun | Volume | 338 |
| Issue | 3 | Pages | 1467-77 |
| PubMed ID | 16271702 | Mgi Jnum | J:103458 |
| Mgi Id | MGI:3609524 | Doi | 10.1016/j.bbrc.2005.10.101 |
| Citation | Kroczynska B, et al. (2005) BIP co-chaperone MTJ1/ERDJ1 interacts with inter-alpha-trypsin inhibitor heavy chain 4. Biochem Biophys Res Commun 338(3):1467-77 |
| abstractText | MTJ1/ERdj1 and its human homologue HTJ1 are membrane proteins that interact with the molecular chaperone BiP through their J-domain. HTJ1 also contains a C-terminal cytosolic region of unknown function that consists of two SANT domains separated by a spacer region. We recently showed that the second SANT domain of HTJ1 (SANT2) binds to alpha1-antichymotrypsin and alters its serpin activity [B. Kroczynska, C.M. Evangelista, S.S. Samant, E.C. Elguindi, S.Y. Blond, The SANT2 domain of the murine tumor cell DnaJ-like protein 1 human homologue interacts with alpha1-antichymotrypsin and kinetically interferes with its serpin inhibitory activity, J. Biol. Chem. 279 (2004) 11432-11443]. Here, we identified a new variant of human inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4) that also interacts with the SANT2 domain of HTJ1. Biochemical, mutagenesis, and fluorescence studies demonstrate that SANT2 binds to a carboxyl-terminal fragment that corresponds to the last third of the new ITIH4 isoform sequence (residues 588-930). ITIH4 and MTJ1 co-immunoprecipitate from total liver protein extracts and SANT2 protects the ITIH4(588-930) recombinant fragment from being processed by kallikrein in vitro. This work reveals that the SANT2 domain of HTJ1 is a genuine protein-protein interaction module. |
