The function of CABYR (calcium binding tyrosine phosphorylation regulated, ENSG00000154040) is as follows. May function as a regulator of both motility- and head- associated functions such as capacitation and the acrosome reaction. Isoform 1 binds calcium in vitro. Isoform 2 and isoform 6 probably bind calcium. Isoform 3 and isoform 5 do not bind calcium in vitro. Isoform 4 probably does not bind calcium.