Synemin

synemin, desmuslin
Identifiers
Symbol	DMN
Entrez	23336
HUGO	24466
OMIM	606087
Other data
Locus	Chr. 15 q26.3

Synemin, also called desmuslin, is an intermediate filament (IF) and, like other IFs, primarily functions to integrate mechanical stress and maintain structural integrity in eukaryotic cells. While it has been observed in a variety of cell types, it has been best studied in the sarcomere of skeletal myocytes. It localizes at the Z-disk and has been shown to bind to α-dystrobrevin, α-actinin, and desmin to act as a mechanical linker in transmitting force laterally throughout the tissue, especially between the contractile myofibrils and extracellular matrix.

Properties

Synemin has properties very similar to the intermediate filament syncoilin. In particular, it binds to α-dystrobrevin in the dystrophin-associated protein complex to act as a mechanical "linker" between the myofibrillar network and the cell membrane.^[1]

Splice Variants

Two splice variant isoforms of synemin exist, α and β. Both isoforms have a very short N-terminal domain of 10 amino acids and a long C-terminal domain consisting of 1243 amino acids for the α isoform and 931 amino acids for the β isoform.^[2] An intronic sequence of the synemin β isoform is used as a coding sequence for synemin α.^[2]

History

The origin of the synemin/desmuslin naming convention is quite complex. In 1980, synemin was first identified in avian smooth muscle and was initially described as an IF-associated protein due to its colocalization and copurification with desmin and vimentin.^[3] Subsequent to the cloning of chicken synemin, Mizuno and colleagues reported the cloning of a novel IF protein, human desmuslin, as an α-dystrobrevin-interacting protein.^[1] Sequence analysis showed that human desmuslin was 32% identical and 11% similar to the amino acid sequence of chicken synemin, while the IF proteins vimentin and desmin are more than 80% identical across the same species. Although several parts were very similar between human desmuslin and chicken synemin, the low degree of conservation between these two proteins compared to other cloned IF proteins suggested that synemin was not the human desmuslin orthologue.^[1] In addition, unlike chicken synemin, in vitro coimmunoprecipitation assays could not detect an interaction between human desmuslin and α-actinin.^[1] In 2001, Titeux and colleagues reported the cloning of the α and β splice-varying isoforms of human synemin and showed that β-synemin was identical to desmuslin.^[2]

References

1. ^ ^{a b c d} Mizuno et al. (2001). "Desmuslin, an intermediate filament protein that interacts with α-dystrobrevin and desmin". Proc Natl Acad Sci USA 98 (11): 6156–61. doi:10.1073/pnas.111153298. PMC 33438. PMID 11353857. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=33438. 
2. ^ ^{a b c} Titeux et al. (2001). "Human synemin gene generates splice variants encoding two distinct intermediate filament proteins". Eur J Biochem 268 (24): 6435–49. doi:10.1046/j.0014-2956.2001.02594.x. PMID 11737198. 
3. ^ Granger & Lazarides; Lazarides, E (1980). "Synemin: a new high molecular weight protein associated with desmin and vimentin filaments in muscle". Cell 22 (3): 727–38. doi:10.1016/0092-8674(80)90549-8. PMID 7006832. 

External links

• MeSH Synemin