F-actin capping protein

{{Infobox protein family

| Symbol = F-actin_cap_A

| Name = F-actin capping protein alpha subunit

| image = PDB 1mwn EBI.jpg

| width =

| caption = solution nmr structure of s100b bound to the high-affinity target peptide trtk-12

| Pfam = PF01267

| Pfam_clan =

| InterPro = IPR018315

| SMART =

| PROSITE = PDOC00609

| MEROPS =

| SCOP = 1izn

| TCDB =

| OPM family =

| OPM protein =

| CAZy =

| CDD =

}}

{{Infobox protein family

| Symbol = F_actin_cap_B

| Name = F-actin capping protein, beta subunit

| image =

| width =

| caption =

| Pfam = PF01115

| Pfam_clan =

| InterPro = IPR001698

| SMART =

| PROSITE = PDOC00203

| MEROPS =

| SCOP = 1izn

| TCDB =

| OPM family =

| OPM protein =

| CAZy =

| CDD =

}}

In molecular biology, the F-actin capping protein is a protein complex which binds in a calcium-independent manner to the fast-growing ends of actin filaments (barbed end), thereby blocking the exchange of subunits at these ends. Unlike gelsolin and severin this protein does not sever actin filaments. The F-actin capping protein is a heterodimer composed of two unrelated subunits: alpha and beta. Neither of the subunits shows sequence similarity to other filament-capping proteins.{{cite journal |vauthors=Maruyama K, Kurokawa H, Oosawa M, Shimaoka S, Yamamoto H, Ito M, Maruyama K | title = Beta-actinin is equivalent to Cap Z protein | journal = J. Biol. Chem. | volume = 265 | issue = 15 | pages = 8712–5 |date=May 1990 | doi = 10.1016/S0021-9258(19)38947-1 | pmid = 2341404 | doi-access = free }} The alpha subunit is a protein of about 268 to 286 amino acid residues and the beta subunit is approximately 280 amino acids, their sequences are well conserved in eukaryotic species.{{cite journal |vauthors=Cooper JA, Caldwell JE, Gattermeir DJ, Torres MA, Amatruda JF, Casella JF | title = Variant cDNAs encoding proteins similar to the alpha subunit of chicken CapZ | journal = Cell Motil. Cytoskeleton | volume = 18 | issue = 3 | pages = 204–14 | year = 1991 | pmid = 1711931 | doi = 10.1002/cm.970180306 }}

The actin filament system, a prominent part of the cytoskeleton in eukaryotic cells, is both a static structure and a dynamic network that can undergo rearrangements: it is thought to be involved in processes such as cell movement and phagocytosis, as well as muscle contraction.