Multifunctional Activity of the Extracellular Domain of the M-type (180 KDa) Membrane Receptor for Secretory Phospholipases A2

M-type (180 kDa) receptors for secretory phospholipases A2 (sPLA2s) are thought to mediate some of the physiological effects of group I sPLA2, including smooth muscle contraction and cell proliferation. The M-type sPLA2 receptor is a large glycoprotein composed of several distinct extracellular domains which belongs to the C-type lectin superfamily. This receptor binds with high affinity both pancreatic group I and inflammatory group II sPLA2s as well as various sPLA2s purified from snake venoms. This paper shows that the rabbit M-type sPLA2 receptor is a multifunctional protein which is able to promote cell adhesion on type I and IV collagens most probably via its N-terminal fibronectin-like type II domain. It also shows that binding of sPLA2s to a recombinant soluble form of this receptor is associated with a noncompetitive inhibition of phospholipase A2 activity.