Identification and purification of a novel phospholipid/ganglioside-binding protein in rabbit serum.

We have isolated a novel phospholipid/ganglioside-binding protein from rabbit sera or platelet-free plasma. Using an affinity chromatography of a commercial gel (Sephacryl S-series gel, Pharmacia) column and a preparative polyacrylamide gel electrophoresis, the protein can be easily purified. The protein agglutinates human red cells irrespective of the ABO blood types, and its hemagglutination reaction is specifically inhibited by some phospholipids (phosphatidylserine and phosphatidylglycerol) and ganglioside (N-acetylneuraminyl-galactosylglucosyl ceramide, GM3). The hemagglutination and its inhibition reactions are independent on any divalent cations (Ca2+, Mg2+, Mn2+, Ni2+). The protein seems to be assembled as multimers of disulfide-bonded molecular of 86 kDa and 59 kDa subunits.