EFHC1 has a molecular mass of 74 kD and contains 3 DM10 domains and an EF-hand calcium-binding motif. Alternative splicing of exon 4 yields 2 transcripts termed A and B; the B transcript results in a C-terminally truncated protein. both transcripts are expressed in various tissues, including brain, but not in lymphocytes.Immunohistochemical analysis showed that staining for the EFCH1 protein overlapped with signals for the Ca(V)2.3 voltage-gated calcium channel (CACNA1E) at neuronal soma and dendrites. Patch-clamp experiments demonstrated that EFHC1 increased the CACNA1E current, suggesting that EFHC1 enhances calcium influx through that channel and stimulates programmed cell death. Expression of EFCH1 mutants in the same system substantially reduced the cell-death effect.