first calponin homology (CH) domain found in the beta spectrin family
The beta spectrin family includes beta-I, -II, -III, -IV and -V spectrins. Spectrin is an actin crosslinking and molecular scaffold protein that links the plasma membrane to the actin cytoskeleton, and functions in the determination of cell shape, arrangement of transmembrane proteins, and organization of organelles. It is composed of two antiparallel dimers of alpha- and beta- subunits. Beta-I spectrin, also called spectrin beta chain, erythrocytic (SPTB), may be involved in anaemia pathogenesis. Beta-II spectrin, also called spectrin beta chain, non-erythrocytic 1 (SPTBN1), or fodrin beta chain, is a component of fodrin, which is the general spectrin-like protein that seems to be involved in secretion. Fodrin interacts with calmodulin in a calcium-dependent manner and is thus a candidate for the calcium-dependent movement of the cytoskeleton at the membrane. Beta-IV spectrin is also called spectrin, non-erythroid beta chain 3 (SPTBN3) or spectrin beta chain, non-erythrocytic 4 (SPTBN4). Its mutation associates with congenital myopathy, neuropathy, and central deafness. Beta-III spectrin is also called spectrin beta chain, non-erythrocytic 2 (SPTBN2), or spinocerebellar ataxia 5 protein (SCA5). Beta-V spectrin, also called spectrin beta chain, non-erythrocytic 5 (SPTBN5), is a mammalian ortholog of Drosophila beta H spectrin. Beta-III and Beta-V spectrins may play crucial roles as longer actin-membrane cross-linkers or fulfill the need for greater extensible flexibility than can be provided by the other smaller conventional spectrins. Members of this family contain two copies of the CH domain. This model corresponds to the first CH domain. CH domains are actin filament (F-actin) binding motifs.
Jiyao W et al.(2023). "The conserved domain database in 2023.",