Actinin is a microfilament protein. α-Actinin is necessary for the attachment of actin filaments to the Z-lines in skeletal muscle cells,[1] and to the dense bodies in smooth muscle cells.[2] The functional protein is an anti-parallel dimer, which cross-links the thin filaments in adjacent sarcomeres, and therefore coordinates contractions between sarcomeres in the horizontal axis.

The non-sarcomeric α-actinins, encoded by ACTN1 and ACTN4, are widely expressed. ACTN2 expression is found in both cardiac and skeletal muscle, whereas ACTN3 is limited to the latter. Both ends of the rod-shaped α-actinin dimer contain actin-binding domains.

Mutations in ACTN4 can cause the kidney disease focal segmental glomerulosclerosis (FSGS).[3]

See also


  1. Ganong's Review of Medical Physiology, 24th Edition. Lange (Tata McGraw Hill). 2012. p. 100.
  2. Laszlo Szekeres; Julius G. Papp (6 December 2012). Pharmacology of Smooth Muscle. Springer Science & Business Media. pp. 17–18. ISBN 978-3-642-78920-5.
  3. Richard P. Lifton; Stefan Somlo; Gerhard H. Giebisch; Donald W. Seldin (25 February 2009). Genetic Diseases of the Kidney. Academic Press. pp. 117–118. ISBN 978-0-08-092427-4.

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