STRUCTURAL AND FUNCTIONAL COMPARISON OF ANCHORIN-CII (CARTILAGE ANNEXIN-V) AND MUSCLE ANNEXIN-V

Annexin V has been isolated from chicken muscle and cartilage either b y EDTA extraction or by plasma membrane purification and solubilizatio n with detergent to obtain the hydrophilic and hydrophobic variants. T he hydrophobic variant of the cartilage annexin V associated with phos phatidylserine-containing liposomes in a Ca2+-independent manner, wher eas the EDTA-extracted molecule required Ca2+ for association with the liposomes. The collagen-binding assay used is based on the principle of a cell attachment assay using mildly pepsinized collagen type II or intact collagen type I as the solid-phase substrate. Soluble intact c ollagen type I or II was added as competitive inhibitor. The lipophili c and the EDTA-extracted anchorins CII from cartilage were inhibited t o the same extent by collagen type II on pepsinized collagen type II a s the solid-phase substrate. The EDTA-extracted muscle annexin V exhib ited a fivefold lower affinity to collagen type II than its counterpar t from cartilage. Peptide mapping studies and amino acid sequencing of selected peptides from the hydrophobic cartilage annexin V and the hy drophilic cartilage and muscle annexin V revealed 100% identity to the established chicken annexin V protein sequence in the corresponding a mino acids 7-29 and 118-126. These results indicate that annexin V may occur in multiple pools within one cell type and/or tissue and that i ts biological function may depend on the subcellular distribution as w ell as the microenvironment in the tissue. (C) 1994 Academic Press, In c.