Intracellular processing of complement pro-C3 and proalbumin is inhibited by rat alpha 1-protease inhibitor variant (Met352----Arg) in transfected cells.
Complement C3, when its cDNA was transfected into COS-1 cells, was synthesized as a precursor, pro-C3, which was intracellularly processed into the alpha and beta subunits, although not completely. A cDNA for rat alpha 1-protease inhibitor (alpha 1-PI) was mutated in vitro to encode its variant with the modified active site (Met352----Arg). In cells co-transfected with the mutant alpha 1-PI cDNA and the C3 cDNA, pro-C3 expressed was secreted without being processed into the subunits. Co-transfection of the mutant alpha 1-PI cDNA and the albumin cDNA also resulted in the inhibition of intracellular conversion of proalbumin into serum-type albumin. No inhibition of the processing of each preform was observed in cells co-transfected with the normal alpha 1-PI cDNA. Taken together, the results indicate that the alpha 1-PI variant (Met352----Arg) expressed inhibits specifically an intracellular enzyme which is involved in the proteolytic processing of both pro-C3 and proalbumin.
Misumi
Y
Y
Department of Biochemistry and Radioisotope Laboratory, Fukuoka University School of Medicine, Japan.
Ohkubo
K
K
Sohda
M
M
Takami
N
N
Oda
K
K
Ikehara
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002522:Chlorocebus aethiops; D003176:Complement C3 / Q000378:metabolism*; D004252:DNA Mutational Analysis; D008969:Molecular Sequence Data; D009841:Oligonucleotides; D011228:Prealbumin / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D051381:Rats; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D014162:Transfection; D000515:alpha 1-Antitrypsin / Q000235:genetics / Q000378:metabolism*
D003176:Complement C3; D009841:Oligonucleotides; D011228:Prealbumin; D011498:Protein Precursors; D011994:Recombinant Proteins; D000515:alpha 1-Antitrypsin