Calumenin interacts with serum amyloid P component

We recently reported the identification of human calumenin, a novel Ca2+ bi nding, transformation-sensitive and secreted protein [Vorum ct al, (1998) B iochim, Biophys, Acta 1386, 121-131; Vorum et al, (1999) Exp. Cell Res. 248 , 4730481] belonging to the family of multiple EF-hand proteins of the secr etory pathway that include reticulocalbin, ERC-55, Cab45 and crocalbin, In order to further investigate the extracellular functions of calumenin we im mobilized the recombinant protein to a column. After application of a place ntal tissue extract we were able to elute one protein that interacts with c alumenin in the presence of Ca2+. Amino acid sequencing identified this pro tein as serum amyloid P component (SAP), Furthermore, we verified and chara cterized the calumenin-SAP interaction by the surface plasmon resonance tec hnique. The findings indicate that calumenin may participate in the immunol ogical defense system and could be involved in the pathological process of amyloidosis that leads to formation of amyloid deposits seen in different t ypes of tissues. (C) 2000 Federation of European Biochemical Societies.