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). Homodimer (in vitro) (PubMed:15476821). Interacts with KCND2 (PubMed:15454437, PubMed:18364354). Identified in a complex with KCND2 and KCNIP2 (PubMed:18364354). Forms an octameric complex composed of four DPP6 subunits bound to the KCND2 tetramer (PubMed:18364354). Expressed predominantly in brain. N-glycosylated. 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. Genetic variation in DPP6 may influence susceptibility to amyotrophic lateral sclerosis (ALS). ALS is a severely disabling and lethal disorder caused by progressive degeneration of motor neurons in the brain, spinal cord and brainstem. Belongs to the peptidase S9B family.