||F-actin-capping proteins bind in a Ca(2+)-independent manner to the fast growing ends of actin filaments (barbed end) thereby blocking the exchange of subunits at these ends. Unlike other capping proteins (such as gelsolin and severin), these proteins do not sever actin filaments. The isoform beta-3 may play a role in spermatogenesis. Alternatively, may play a role in later maturation steps such as capacitation and fertilization which involve changes of membrane domains. May play a role in the regulation of cell morphology and cytoskeletal organization.
||Cytoplasm, cytoskeleton, perinuclear theca, calyx
||F-actin-capping protein beta subunit family
||The isoform beta-3 is predominantly expressed in the testis. It is only detected in total sperm, sperm heads and the calyx fraction, but not in sperm tails or any supernatant fraction. Weaker expression also found in brain.