Spectrin beta III (SPTBN2)

Spectrin is an actin binding protein that is a major component of the plasma membrane skeleton. Spectrins function as membrane organizers and stabilizers by forming dimers, tetramers and higher polymers. Vertebrate spectrins have two alpha-subunits (alpha-I/alpha-II), four beta-subunits (beta-I-beta-IV) and a beta-H subunit creating diversity and specialization of function. Spectrin alpha and spectrin beta are present in erythrocytes, whereas spectrin alpha II (also designated fodrin alpha) and spectrin beta I (also designated fodrin beta) are present in other somatic cells. The spectrin tetramers in erythrocytes act as barriers to lateral diffusion, but spectrin dimers seem to lack this function. Spectrin beta III is highly homologous to both spectrin beta I and spectrin beta II. Spectrin beta III is highly expressed in brain, kidney, pancreas and liver, and at lower levels in lung and placenta. Spectrin beta 3 is primarily expressed in nervous tissues with highest expression levels in the cerebellum, where it is found in Purkinje cell soma and dendrites.

[spectrin beta chain, non-erythrocytic 2; Spectrin beta chain, non-erythrocytic 2; spectrin beta chain, non-erythrocytic 2; spectrin beta, non-erythrocytic 2; Beta-III spectrin; Spinocerebellar ataxia 5 protein]