P11, A UNIQUE MEMBER OF THE S100 FAMILY OF CALCIUM-BINDING PROTEINS, INTERACTS WITH AND INHIBITS THE ACTIVITY OF THE 85-KDA CYTOSOLIC PHOSPHOLIPASE A(2)

Using a two hybrid system screen of a human cDNA library, we have foun d that pll, a unique member of the S100 family of calcium-binding prot eins, interacts with the carboxyl region of the 85-kDa cytosolic phosp holipase A(2) (cPLA(2)), p11 synthesized in a cell-free system interac ts with cPLA(2) in vitro, The p11-cPLA(2) complex is detectable from a human bronchial epithelial cell line (BEAS 2B), Furthermore, pll inhi bits cPLA(2) activity in vitro, Selective inhibition of pll expression in the BEAS 2B cells by antisense RNA results in an increased PLA(2) activity as well as an increased release of prelabeled arachidonic aci d, This study demonstrates a novel mechanism for the regulation of cPL A(2) by an S100 protein.