The invention provides isolated nucleic acids molecules, designated PCIP nucleic
acid molecules, which encode proteins that bind potassium channels and modulate
potassium channel mediated activities. The invention also provides antisense nucleic
acid molecules, recombinant expression vectors containing PCIP nucleic acid molecules,
host cells into which the expression vectors have been introduced, and nonhuman
transgenic animals in which a PCIP gene has been introduced or disrupted. The invention
still further provides isolated PCIP proteins, fusion proteins, antigenic peptides
and anti-PCIP antibodies. Diagnostic methods utilizing compositions of the invention
are also provided.