Selective cell-surface expression of dipeptidyl peptidase IV with mutations at the active site sequence.
The cell surface expression of dipeptidyl peptidase IV (DPPIV) was examined in COS-1 cells transfected with its cDNA with or without mutations at the active site sequence Gly-Trp-Ser-Tyr-Gly (positions 629-633). Mutants with substitution of Trp630----Glu or Ser631----Ala were expressed on the cell surface as normally as the wild-type DPPIV, although the mutant with Ala631 had no enzyme activity. In contrast, any single substitutions of Gly at positions 629 and 633 resulted in no surface expression of the mutants, which were, instead, detected within the cells. When Tyr632 was substituted, one mutant (Tyr----Phe) was expressed on the surface, whereas the others (Tyr----Gly or Leu) were intracellularly retained. These results indicate that the surface expression of DPPIV is critically influenced by mutations at the active site sequence.
Department of Biochemistry, Fukuoka University School of Medicine, Japan.
T
T
Fujiwara
E
E
Tsuji
Y
Y
Misumi
N
N
Takami
Y
Y
Ikehara
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002462:Cell Membrane / Q000201:enzymology*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
D011994:Recombinant Proteins; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4