it is a nonspecific cation channel, which means that both sodium and calcium ions can pass through it. trpc1 is thought to mediate calcium entry in response to depletion of endoplasmic calcium stores or activation of receptors coupled to the phospholipase c system. in hek293 cells the unitary current-voltage relationship of endogenous trpc1 channels is almost linear, with a slope conductance of about 17 ps. the extrapolated reversal potential of trpc1 channels is +30 mv.