Molecular characterization of a novel dipeptidyl peptidase like 2-short form (DPL2-s) that is highly expressed in the brain and lacks dipeptidyl peptidase activity.
DPL2 (DPP10) found at chromosome 2q14.1 is a member of the dipeptidyl peptidase IV (DPIV) gene family. Here we characterize a novel short DPL2 isoform (DPL2-s), a 789-amino acid protein, that differs from the previously described long DPL2 isoform (DPL2-l) at the N-terminal cytoplasmic domain by 13 amino acids. The two DPL2 isoforms use alternate first exons. DPL2 mRNA was expressed mainly in the brain and pancreas. Multiple forms of recombinant DPL2-s protein were observed in 293T cells, having mobilities 96 kDa, 100 kDa, and approximately 250 kDa which may represent soluble DPL2, transmembrane DPL2 and multimeric DPL2 respectively. DPL2 is glycosylated as a band shift is observed following PNGase F deglycosylation. DPL2-s was expressed primarily on the cell surface of transfected 293T and PC12 cells. DPL2-s exhibits high sequence homology with other DPIV peptidases, but lacks a catalytic serine residue and lacks dipeptidyl peptidase activity. Substitutions of Gly(644)-->Ser, Lys(643)Gly(644)-->TrpSer, or Asp(561)Lys(643)Gly(644)-->TyrTrpSer in the catalytic motif did not confer dipeptidyl peptidase activity upon DPL2-s. Thus, although DPL2 is similar in structure and sequence to the other dipeptidyl peptidases, it lacks vital residues required to confer dipeptidyl peptidase activity and has instead evolved features that enable it to act as an important component of voltage-gated potassium channels.
Chen
Tong
T
School of Biological Sciences, Flinders University, GPO BOX 2100, Adelaide, South Australia 5001, Australia.
Ajami
Katerina
K
McCaughan
Geoffrey W
GW
Gai
Wei-Ping
WP
Gorrell
Mark D
MD
Abbott
Catherine A
CA
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000201:enzymology*; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000201:enzymology; D018076:DNA, Complementary / Q000235:genetics; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D006031:Glycosylation; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010179:Pancreas / Q000201:enzymology; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D018076:DNA, Complementary; D007527:Isoenzymes; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger; D011994:Recombinant Proteins; C476879:DPP10 protein, human; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases