Crocalbin: a new calcium‐binding protein that is also a binding protein for crotoxin, a neurotoxic phospholipase A₂

Abstract

Utilizing Marathon-ready cDNA library and a genespecific primer corresponding to a partial amino acid sequence determined previously, the complete nucleotide sequence for the cDNA of crocalbin, which binds crotoxin (a phospholipase A 2 ) and Ca 2+ , was obtained by polymerase chain reaction. The open reading frame of the cDNA encodes a novel polypeptide of 315 amino acid residues, including a signal sequence of 19 residues. This protein contains six potential Ca 2+ -binding domains, one Nglycosylation site, and a large amount of acidic amino acid residues. The ability to bind Ca 2+ has been ascertained by calcium overlay experiment. Evidenced by sequence similarity in addition, it is concluded that crocalbin is a new member of the reticulocalbin family of calcium-binding proteins.z 1999 Federation of European Biochemical Societies.

Distribution and Variable Expression of Secretory Pathway Protein Reticulocalbin in Normal Human Organs and Non-neoplastic Pathological Conditions

“…In addition to RCN, the RCN family proteins include ERC55 (Weis et al 1994), crocalbin (Hseu et al 1999), Cab45 (Vorum et al 1998), and calumenin (Koivu et al 1997). RCN and ERC55 are strictly localized to the ER, Cab45 is localized to the Golgi complex, and calumenin is distributed throughout the whole secretory pathway.…”

Molecular evolution and structure–function relationships of crotoxin-like and asparagine-6-containing phospholipases A2 in pit viper venoms

“…Several binding proteins of crotoxin on the neuronal or presynaptic membrane of mammalian brain have been characterized [16,50], but the mechanism by which crotoxin blocks neurotransmitter release remains obscure [51]. Calmodulin, a ubiquitous and cytosolic protein, binds a large range of proteins [16], probably via its hydrophobic and acidic domains [52,53].…”

“…In fact, RVV-PL-VIII and most of the non-neurotoxic N6-PLA 2 s contain KK or KR at positions 115-116, whereas CB has YG. Thus the positively charged 115-116 residues probably contribute to the myotoxicity rather than neurotoxicity of the PLA 2 s. Other specific binding proteins of crotoxin on the presynaptic membrane [50] related to exocytosis should be investigated.…”

Caracterización biológica y acción de inhibidores de una fosfolipasa A2 del veneno de Lachesis muta

“…Esto permite afirmar que la enzima requiere de iones como calcio para potenciar su actividad (Hseu et al 1999). Así mismo, debemos resaltar el hecho que los ácidos aspártico y glutámico logran inhibir a la PLA 2 a altas concentraciones, por lo que se sospecha que el mecanismo de acción comprendería la atracción del ion ligado a la enzima por tales aminoácidos ácidos, causando con ello un descenso en la afinidad PLA 2 -fosfolipidos.…”