TY  - JOUR
A1  - Martin, Virginie
A1  - Groenendyk, Jody
A1  - Steiner, Simone S.
A1  - Guo, Lei
A1  - Dabrowska, Monika
A1  - Robert Parker, J.M.
A1  - Müller-Esterl, Werner
A1  - Opas, Michal
A1  - Michalak, Marek
T1  - Identification by mutational analysis of amino acid residues essential in the chaperone function of calreticulin
T2  - Journal of biological chemistry
N2  - Calreticulin is a Ca2+ -binding chaperone that resides in the lumen of the endoplasmic reticulum and is involved in the regulation of intracellular Ca2+ homeostasis and in the folding of newly synthesized glycoproteins. In this study, we have used site-specific mutagenesis to map amino acid residues that are critical in calreticulin function. We have focused on two cysteine residues (Cys(88) and Cys(120)), which form a disulfide bridge in the N-terminal domain of calreticulin, on a tryptophan residue located in the carbohydrate binding site (Trp(302)), and on certain residues located at the tip of the "hairpin-like" P-domain of the protein (Glu(238), Glu(239), Asp(241), Glu(243), and Trp(244)). Calreticulin mutants were expressed in crt(-/-) fibroblasts, and bradykinin-dependent Ca2+ release was measured as a marker of calreticulin function. Bradykinin-dependent Ca2+ release from the endoplasmic reticulum was rescued by wild-type calreticulin and by the Glu(238), Glu(239), Asp(241), and Glu(243) mutants. The Cys(88) and Cys(120) mutants rescued the calreticulin-deficient phenotype only partially ( approximately 40%), and the Trp(244) and Trp(302) mutants did not rescue it at all. We identified four amino acid residues (Glu(239), Asp(241), Glu(243), and Trp(244)) at the hairpin tip of the P-domain that are critical in the formation of a complex between ERp57 and calreticulin. Although the Glu(239), Asp(241), and Glu(243) mutants did not bind ERp57 efficiently, they fully restored bradykinin-dependent Ca2+ release in crt(-/-) cells. This indicates that binding of ERp57 to calreticulin may not be critical for the chaperone function of calreticulin with respect to the bradykinin receptor.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/76245
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-762456
SN  - 0021-9258
VL  - 281.2006
IS  - 4
SP  - 2338
EP  - 2346
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -