Vascular anticoagulant β: a novel human Ca2+/phospholipid binding protein that inhibits coagulation and phospholipase A2 activity

A cDNA was cloned coding for a new member of the human Ca2+-modulated phospholipid-binding protein family termed annexins. Due to its 56% identity to the human vascular anticoagulant (VAC) the new protein is named VAC-β, renaming the previous VAC as VAC-α. Northern analysis detects one hybridizing mRNA species of 2.2 kb in human placenta. Genomic Southern blot analysis shows a VAC-β gene of comparable complexity to the VAC-α gene. The cDNA was expressed in Escherichia coli and the recombinant protein purified to homogeneity. Antiserum raised against VAC-β weakly cross-reacts with VAC-α. The properties of VAC-β as an anticoagulant and as an inhibitor of phospholipase A2 activity were analyzed and compared to those of VAC-α.