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From Proteopedia
Structure of a human A-type Potassium Channel Accelerating factor DPPX, a member of the dipeptidyl aminopeptidase family
Structural highlights
DiseaseDPP6_HUMAN Autosomal dominant primary microcephaly;Idiopathic ventricular fibrillation, non Brugada type. The disease is caused by variants affecting the gene represented in this entry. A genetic variation 340 bases upstream from the ATG start site of the DPP6 gene is the cause of familial paroxysmal ventricular fibrillation type 2. The disease is caused by variants affecting the gene represented in this entry. FunctionDPP6_HUMAN Promotes cell surface expression of the potassium channel KCND2 (PubMed:15454437, PubMed:19441798). Modulates the activity and gating characteristics of the potassium channel KCND2 (PubMed:18364354). Has no dipeptidyl aminopeptidase activity (PubMed:8103397, PubMed:15476821).[1] [2] [3] [4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIt has recently been reported that dipeptidyl aminopeptidase X (DPPX) interacts with the voltage-gated potassium channel Kv4 and that co-expression of DPPX together with Kv4 pore forming alpha-subunits, and potassium channel interacting proteins (KChIPs), reconstitutes properties of native A-type potassium channels in vitro. Here we report the X-ray crystal structure of the extracellular domain of human DPPX determined at 3.0A resolution. This structure reveals the potential for a surface electrostatic change based on the protonation state of histidine. Subtle changes in extracellular pH might modulate the interaction of DPPX with Kv4.2 and possibly with other proteins. We propose models of DPPX interaction with the voltage-gated potassium channel complex. The dimeric structure of DPPX is highly homologous to the related protein DPP-IV. Comparison of the active sites of DPPX and DPP-IV reveals loss of the catalytic serine residue but the presence of an additional serine near the "active" site. However, the arrangement of residues is inconsistent with that of canonical serine proteases and DPPX is unlikely to function as a protease (dipeptidyl aminopeptidase). Structure of a human A-type potassium channel interacting protein DPPX, a member of the dipeptidyl aminopeptidase family.,Strop P, Bankovich AJ, Hansen KC, Garcia KC, Brunger AT J Mol Biol. 2004 Oct 29;343(4):1055-65. PMID:15476821[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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