Identification and Purification of a Novel Receptor for Secretory Phospholipase A2 in Porcine Cerebral Cortex

• Published in: The Journal of biological chemistry Vol. 274; no. 37; pp. 26315 - 26320
• Main Authors: Copic, A, Vucemilo, N, Gubensek, F, Krizaj, I
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 10-09-1999; American Society for Biochemistry and Molecular Biology
• Subjects: ammodytoxin c; binding; binding proteins; cerebral cortex; glycoproteins; immunocytochemistry; liver; molecular weight; neurotoxins; phospholipase A2; purification; receptors; swine; venoms; Vipera; vipera ammodytes
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.37.26315

A specific phospholipase A2receptor from porcine cerebral cortex has been characterized (Kd = 145 nm, Bmax = 0.4 pmol/mg membrane protein) by using a radioiodinated derivative of ammodytoxin C (AtxC), a snake venom presynaptically neurotoxic group IIA phospholipase A2. After the receptor was solubilized in a ligand-binding form, it was approximately 14,000-fold enriched by chromatography on wheat germ lectin-Sepharose and AtxC-Affi-Gel 10. The receptor is a single chain glycoprotein with an apparent molecular mass of 180 kDa and binds toxic and non-toxic phospholipases A2 of either group I or II. It also recognizes conjugates of bovine serum albumin with mannose, N-acetylglucosamine, and galactose. In its molecular mass and pharmacological profile, the AtxC receptor resembles the M-type receptor for secretory phospholipases A2 from rabbit skeletal muscle (a C-type multilectin, homologous to macrophage mannose receptor), yet in terms of relative abundance in brain and antigenicity, these two receptors are completely different. A further AtxC receptor of approximately 200 kDa discovered in porcine liver was, however, recognized by anti-rabbit M-type phospholipase A2receptor antibodies. There are, therefore, two immunologically distinct secretory phospholipase A2 receptors of about 200 kDa in the same species. Although the liver receptor is related to the M-type secretory phospholipase A2 receptors, the brain receptor is not and belongs to a novel group of secretory phospholipase A2 receptors.