CLONING OF THE CDNA-ENCODING HUMAN PLATELET-CD36 - COMPARISON TO PCR AMPLIFIED FRAGMENTS OF MONOCYTE, ENDOTHELIAL AND HEL CELLS

Glycoprotein CD36, also known as GPIIIb or GPIV, is a major platelet g lycoprotein that bears the newly identified Nak(a) alloantigen. The ai m of this study was to clone platelet CD36 and investigate other forms of CD36-cDNA present in monocytes, endothelial and HEL cells. RNA fro m above mentioned cells were reverse transcribed (RT), using specific primers for CD36, and amplified by the polymerase chain reaction (PCR) technique. Sequencing the different amplified platelet derived cDNA f ragments, spanning the whole coding and flanking regions, showed the n ear identity between platelet and CD36-placenta cDNA. Platelet CD36-cD NA cross-hybridized, in Southern blots, with RT-PCR amplified cDNA ori ginating from monocytes, endothelial and HEL cells. However, monocytes showed a RT-PCR amplified cDNA fragment (561 bp) that was present in platelets and placenta but not on endothelial on HEL-cells. Northern b lot analysis of platelet RNA hybridized with placenta CD36 indicated t he presence of a major (1.95 kb) and a minor (0.95 kb) transcript. The 1.95 kb transcript was the only one observed on Northern blots of mon ocytes, endothelial and HEL cells. These results indicate that the str ucture of CD36 expressed in platelets is similar, with the exception o f the 3' flanking region, to that of placenta. Differences in apparent molecular weight between CD36 and CD36-like glycoproteins may be due to post-translational modifications.