8.A.15 The K+ Channel Accessory Protein (KChAP) Family

The KChAP family consists of proteins from yeast, plants and animals. The best characterized homologues are from mammals. KChAP interacts with the Kv2 principal subunits of the VIC superfamily, enhancing current levels and surface expression of Kv2 without affecting gating or kinetics. It may function as a chaperone subunit.



Coetzee, W.A., Y. Amalillo, J. Chiu, A. Chow, D. Lau, T. McCormack, H. Moreno, M.S. Nadal, A. Ozaita, D. Pountney, M. Saganich, E. Vega-Saenz de Miera, and B. Rudy (1999). Molecular diversity of K+ channels. Ann. N.Y. Acad. Sci USA 868: 233-285.

Mangubat, E.Z., T.-T. Tseng, and E. Jakobsson. (2003). Phylogenetic analyses of potassium channel auxiliary subunits. J. Mol. Microbiol. Biotechnol. (in press).


TC#NameOrganismal TypeExample

K+ channel auxiliary subunit (KChAP) of 628 aas; almost identical to the human ortholog with acc # B3KNI3.  It is also called E3 SUMO-protein ligase PIAS3 isoform X1 or protein inhibitor of activated STAT 3, isoform CRA_b.


KChAP of Mus musculus


Zinc finger MIZ domain-containing protein 2, isoform X4 of 897 aas, zf-MIZ or ZMIZ2. Shows extensive sequence similarity with 8.A.15.1.1 with residues 517 - 677 in the former protein aligning with residues 276 - 425 of the latter with a score of e-18 in TC BLAST.  No function related to a transporter has been identified.

zf-MIZ2 of Homo sapiens


Uncharacterized protein of 530 aas; may be a SUMO ligase. 

UP of Paracoccidioides brasiliensis


Uncharacterized protein of 887 aas.

UP of Oryza sativa subsp. indica (Rice)