module: dmel_f_actin_capping_protein
title: F-actin capping protein (CapZ) in Drosophila melanogaster
label: F-actin capping protein
module_type: PROTEIN_COMPLEX
description: >-
  Capping protein is an alpha/beta heterodimer that binds the barbed (plus) end of
  actin filaments with high affinity and blocks the addition and loss of actin
  subunits there. It limits filament elongation, which shapes branched actin
  networks and controls the length of actin structures. In Drosophila the alpha
  (cpa) and beta (cpb) subunits are each required to restrict actin filament
  growth, for example in bristle development and in the germline, and loss of
  either subunit destabilizes the other. The same heterodimer also caps the
  barbed end of the Arp1 filament of dynactin.
summary: >-
  Alpha/beta heterodimer that caps actin filament barbed ends.
concepts:
  - {id: GO:0008290, label: F-actin capping protein complex}
parts:
  - id: capping_protein_alpha
    label: Capping protein alpha subunit
    role: alpha subunit of the heterodimer
    genes: [cpa]
    processes:
      - {id: GO:0051016, label: barbed-end actin filament capping}
  - id: capping_protein_beta
    label: Capping protein beta subunit
    role: beta subunit of the heterodimer
    genes: [cpb]
    processes:
      - {id: GO:0051016, label: barbed-end actin filament capping}
notes: >-
  cpa and cpb are also members of the FlyBase dynactin complex group, where the
  heterodimer caps the Arp1 filament; they appear in both modules. The barbed-end
  capping activity belongs to the heterodimer as a whole, so no molecular function
  is assigned to the individual subunits.
group: ACPC
function_note: >-
  The GO barbed-end actin capping activity terms are obsolete, so no
  complex-level molecular function is assigned either.