Thought to form non-selective a receptor-activated calcium permeant cation channel. Probably is operated by a phosphatidylinositol second messenger system activated by receptor tyrosine kinases or G-protein coupled receptors. Acts as a cell-cell contact-dependent endothelial calcium entry channel. Has also been shown to be calcium-selective (By similarity). May also be activated by intracellular calcium store depletion. Homotetramer and heterotetramer with TRPC1 and/or TRPC5 (PubMed:12857742). Isoform alpha but not isoform beta interacts with ITPR1, ITPR2 and ITPR3 (By similarity). Interacts with SLC9A3R1/NHERF (By similarity). Interacts with MX1 and RNF24 (By similarity). Interacts (via CIRB domain) with SESTD1 (via the spectrin 1 repeat) and SPTBN5 (via C-terminus) (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). Belongs to the transient receptor (TC 1.A.4) family. STrpC subfamily. TRPC4 sub-subfamily.