MULTIFUNCTIONAL ACTIVITY OF THE EXTRACELLULAR DOMAIN OF THE M-TYPE (180 KDA) MEMBRANE-RECEPTOR FOR SECRETORY PHOSPHOLIPASES A(2)

M-type (180 kDa) receptors for secretory phospholipases A(2) (sPLA(2)s ) are thought to mediate some of the physiological effects of group I sPLA(2), including smooth muscle contraction and cell proliferation. T he M-type sPLA(2) receptor is a large glycoprotein composed of several distinct extracellular domains which belongs to the C-type lectin sup erfamily. This receptor binds with high affinity both pancreatic group I and inflammatory group II sPLA(2)s as well as various sPLA(2)s puri fied from snake venoms. This paper shows that the rabbit M-type sPLA(2 ) receptor is a multifunctional protein which is able to promote cell adhesion on type I and IV collagens most probably via its N-terminal f ibronectin-like type II domain. It also shows that binding of sPLA(2)s to a recombinant soluble form of this receptor is associated with a n oncompetitive inhibition of phospholipase A(2) activity.