Thought to form a receptor-activated non-selective calcium permeant cation channel. Probably is operated by a phosphatidylinositol second messenger system activated by receptor tyrosine kinases or G-protein coupled receptors. Has also been shown to be calcium-selective. May also be activated by intracellular calcium store depletion. Acts as a cell-cell contact-dependent endothelial calcium entry channel (By similarity). Homotetramer and heterotetramer with TRPC1 and/or TRPC5 (By similarity). Isoform alpha interacts with ITPR1, ITPR2 and ITPR3 (By similarity). Interacts with (via the PDZ-binding domain) with SLC9A3R1/NHERF (By similarity). Interacts with MX1 and RNF24 (By similarity). Interacts (via CIRB domain) with SESTD1 (via the spectrin 1 repeat) (By similarity). Interacts with CDH5 and CTNNB1 (By similarity). Interacts (via protein 4.1-binding domain) with EPB41L2 (By similarity). Interacts with TRPC4AP (By similarity). Interacts with PLSCR1 (By similarity). Expressed in adrenal gland. Lower expression in heart and retina. Also expressed in testis. The short isoform is specifically expressed in the adrenal gland. Belongs to the transient receptor (TC 1.A.4) family. STrpC subfamily. TRPC4 sub-subfamily. Extended N-terminus.