Mapping human calreticulin regions important for structural stability

Calreticulin (CALR) is a highly conserved multifunctional chaperone protein primarily present in the endoplasmic reticulum, where it regulates Ca2+ homeostasis. Recently, CALR has gained special interest for its diverse functions outside including cell surface and extracellular space. Although high-resolution structures of exist, not yet been established how different regions individual amino acid residues contribute to structural stability protein. In study, we have identified key determining CALR. We used Saccharomyces cerevisiae expression system express purify 50 human mutants, which were analysed several parameters secretion titer, melting temperature (Tm), oligomeric state. Our results revealed importance previously small patch residues, acids 166–187 (“cluster 2”) Two Tyr172 Asp187, critical maintaining native structure Mutant D187A severe drop was thermally unstable, prone degradation, oligomer formation. thermal interacted with third free Cys163 residue. This illustrates an unusual dominated by Cys163, may interact as part unit. Besides clusters, found correlation some measured parameter values groups mutants that cause myeloproliferative neoplasms (MPN) be associated sudden unexpected death (SUD).