Annexin V is a member of a new family of calcium-dependent phospholipid-binding proteins. It has been previously isolated as placental anticoagulant protein I, inhibitor of blood coagulation, vascular anticoagulant-alpha, endonexin II, lipocortin V, placental protein 4, and anchorin CII. The human gene encoding annexin V (ANX5) was localized to 4q26 --> q28 by in situ hybridization with a cDNA probe and polymerase chain-reaction (PCR) analysis of a human x hamster hybrid cell panel. The regional localization to 4q26 --> q28 was supported by Southern-blot analysis of a human cell line with a deletion in 4q23 --> q27. This localization overlaps but differs slightly from the previous assignment of ANX5 to 4q28 --> q32. Digestion with PvuII and TaqI identified polymorphisms at the ANX5 locus; the PvuII polymorphism could also be detected by PCR analysis.