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. 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. Trpc4 deficient mice lack a store-operated calcium entry in endothelial cells. Homotetramer (PubMed:19070363). Heterotetramer with TRPC1 and/or TRPC5 (By similarity). 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 (PubMed:20458742). Interacts with PLSCR1 (PubMed:32110987). Abundantly expressed in brain (hippocampal CA1 pyramidal neurons, dentate gyrus granule cells, and cerebral cortical neurons, and in the septal nuclei and the mitral layer of olfactory bulb). Lower levels are detected in other tissues. Belongs to the transient receptor (TC 1.A.4) family. STrpC subfamily. TRPC4 sub-subfamily.