The sarcoglycans are a family of
transmembrane protein
A transmembrane protein is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequently un ...
s
(α, β, γ, δ or ε) involved in the
protein complex
A protein complex or multiprotein complex is a group of two or more associated polypeptide chains. Protein complexes are distinct from multidomain enzymes, in which multiple active site, catalytic domains are found in a single polypeptide chain.
...
responsible for connecting the muscle fibre
cytoskeleton
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is compos ...
to the
extracellular matrix
In biology, the extracellular matrix (ECM), also called intercellular matrix (ICM), is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and bio ...
, preventing damage to the muscle fibre
sarcolemma
The sarcolemma (''sarco'' (from ''sarx'') from Greek; flesh, and ''lemma'' from Greek; sheath), also called the myolemma, is the cell membrane surrounding a skeletal muscle fibre or a cardiomyocyte.
It consists of a lipid bilayer and a thin ...
through shearing forces.
The
dystrophin
Dystrophin is a rod-shaped cytoplasmic protein, and a vital part of a protein complex that connects the cytoskeleton of a muscle fiber to the surrounding extracellular matrix through the cell membrane. This complex is variously known as the costa ...
glycoprotein complex (DGC) is a membrane-spanning complex that links the interior cytoskeleton to the extracellular matrix in muscle. The sarcoglycan complex is a subcomplex within the DGC and is composed of six muscle-specific, transmembrane proteins (alpha-, beta-, gamma-, delta-, epsilon-,and zeta-sarcoglycan).
The sarcoglycans are asparagine-linked glycosylated proteins with single transmembrane domains.
The disorders caused by the mutations of the sarcoglycans are called
sarcoglycanopathies. Mutations in the α, β, γ or δ genes (not ε) encoding these proteins can lead to the associated
limb-girdle muscular dystrophy.
Genes
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SGCA
*
SGCB
*
SGCD
*
SGCE
*
SGCG
*
SGCZ
References
Protein families
{{protein-stub