Identification of HIV-1 protease cleavage site in human C1-inhibitor.
We have investigated the ability of HIV-1 protease to cleave human complement proteins of the classical complement pathway: C1q, C2 and C4 as well as the regulatory protein, C1-inhibitor. Purified complement proteins were incubated with recombinant HIV-1 protease in vitro and analyzed by SDS-PAGE and immunoblotting assay. The only cleavage site was found in N-terminal region of C1-inhibitor, and it was located between residues Leu-32 and Phe-33 as determined by amino acid sequence analysis of the 85 kDa proteolytic fragment after 12 Edman degradation cycles. The HIV-1 protease cleavage sites were not found in C1q, C2 and C4 protein. HIV-1 protease-susceptible site in N-terminal region of C1-inhibitor is very close to the cleavage sites of some other proteases that are able to induce N-terminal proteolysis of the protein.
Tissue typing Centre, Department of Cellular Immunology, University Hospital KBC, HR-10000 Zagreb, Kispaticeva 12, Croatia. gerencm@baxter.com
Marijan
M
Gerencer
Vitomir
V
Burek
D000595:Amino Acid Sequence; D003174:Complement C1 Inactivator Proteins; D050718:Complement C1 Inhibitor Protein; D015922:Complement C1q / Q000302:isolation & purification / Q000378:metabolism; D003175:Complement C2 / Q000302:isolation & purification / Q000378:metabolism; D003181:Complement C4 / Q000302:isolation & purification / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D016333:HIV Protease / Q000378:metabolism*; D015151:Immunoblotting; D015843:Serpins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
D003174:Complement C1 Inactivator Proteins; D050718:Complement C1 Inhibitor Protein; D003175:Complement C2; D003181:Complement C4; C469952:SERPING1 protein, human; D015843:Serpins; D015922:Complement C1q; D016333:HIV Protease