The C-terminus of human Cav2.3 voltage-gated calcium channel interacts with alternatively spliced calmodulin-2 expressed in two human cell lines

► Novel calmodulin splice variant (CaM-2-ext) with an extended amino-terminus detected. ► Transcripts of CaM-2-ext are expressed in two tested human cell lines in low amounts. ► The N-terminal extension is hydrophobic, to keep CaM-2-ext membrane-associated. ► CaM-2-ext coprecipitates with overexpressed C-terminus of Cav2.3 in HEK-293 cells. ► CaM-2-ext but not canonical CaM interacts functionally with Cav2.3 in HEK-293 cells.