Chen Tong, Ajami Katerina, McCaughan Geoffrey W, Gai Wei-Ping, Gorrell Mark D, Abbott Catherine A
School of Biological Sciences, Flinders University, GPO BOX 2100, Adelaide, South Australia 5001, Australia.
Biochim Biophys Acta. 2006 Jan;1764(1):33-43. doi: 10.1016/j.bbapap.2005.09.013. Epub 2005 Oct 28.
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.
位于2号染色体q14.1的DPL2（DPP10）是二肽基肽酶IV（DPIV）基因家族的成员。在此，我们鉴定了一种新型的短DPL2异构体（DPL2-s），它是一种789个氨基酸的蛋白质，在N端胞质结构域与先前描述的长DPL2异构体（DPL2-l）相差13个氨基酸。这两种DPL2异构体使用不同的首个外显子。DPL2 mRNA主要在脑和胰腺中表达。在293T细胞中观察到多种形式的重组DPL2-s蛋白，其迁移率分别为96 kDa、100 kDa和约250 kDa，可能分别代表可溶性DPL2、跨膜DPL2和多聚体DPL2。DPL2是糖基化的，因为在PNGase F去糖基化后观察到条带迁移。DPL2-s主要在转染的293T和PC12细胞的细胞表面表达。DPL2-s与其他DPIV肽酶具有高度的序列同源性，但缺乏催化丝氨酸残基且缺乏二肽基肽酶活性。催化基序中的Gly(644)-->Ser、Lys(643)Gly(644)-->TrpSer或Asp(561)Lys(643)Gly(644)-->TyrTrpSer替换并未赋予DPL2-s二肽基肽酶活性。因此，尽管DPL2在结构和序列上与其他二肽基肽酶相似，但它缺乏赋予二肽基肽酶活性所需的关键残基，反而进化出了使其能够作为电压门控钾通道重要组成部分的特性。
