The specific roles of the classical transient receptor potential (TRPC) subfamily, TRPC1, 3, 4, 5, 6 and 7 in arterial smooth muscle (ASM) function are still elusive. We studied therefore heterologously-expressed TRPC1 and TRPC1 gene-deficient mice (TRPC1^-/-). We found that recombinant TRPC1 is not able to build functional homomeric channels. Instead, TRPC1 was able to form functional heteromeric channel complexes with TRPC4 and 5, but not with TRPC3, 6 and 7. In both TRPC1/4 and TRPC1/5 heteromers, TRPC1 subunits significantly decreased Ca²⁺ permeation. Changes of the amino acids in the putative pore forming region of TRPC1 further reduced the Ca²⁺ permeability. Using vascular smooth muscle cells and arteries from TRPC1^-/- mice we found no evidence for an involvement of TRPC1 in mechanosensitivity or store-operated cation influx, nor an influence on Ca²⁺ sparks or spontaneous transient outward currents. Furthermore, deficiency of TRPC1 did not affect a1-adrenoceptor-induced contractions of arteries. We conclude that TRPC1 is able to form heteromeric TRP channels with TRPC4 and 5 with a reduced Ca²⁺ permeability. However, TRPC1 alone or in combination with TRPC4 and 5 is not an obligatory component of store- and receptor-operated Ca²⁺ influx in ASM.