CLEAVAGE OF THE COMPLEMENT-SYSTEM C3 COMPONENT BY HIV-1 PROTEINASE

The C3 factor of the complement system and its C3b fragment are cleave d in vitro by the proteinase of the human immunodeficiency virus, type 1 (HIV PR). The cleavage occurs in the alpha-chain of both substrates at multiple sites yielding a 100 kDa fragment of the C3 alpha-chain a nd multiple fragments of the C3b alpha-chain. The scissile bonds are: Ala86-Glu87, Leu310-Leu311, His641-Trp642 and Ag649-Ser650. The result ing fragments resemble the physiologically occurring inactive fragment s of C3:C3c and C3d, suggesting a possible biological role of the HIV- proteinase in the complement inactivation process.