The sarcoglycans are a family of

transmembrane protein A transmembrane protein (TP) 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 frequent ...

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 multienzyme complexes, in which multiple catalytic domains are found in a single polypeptide chain. Protein ...

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 co ...

to the

extracellular matrix In biology, the extracellular matrix (ECM), also called intercellular matrix, is a three-dimensional network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide s ...

, 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 fiber or a cardiomyocyte. It consists of a lipid bilayer and a thin oute ...

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 cost ...

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 The sarcoglycanopathies are a collection of diseases resulting from mutations in any of the five sarcoglycan genes: α, β, γ, δ or ε. The five sarcoglycanopathies are: α-sarcoglycanopathy, LGMD2D; β-sarcoglycanopathy, LGMD2E; γ-sarcoglycano ...

. Mutations in the α, β, γ or δ genes (not ε) encoding these proteins can lead to the associated limb-girdle muscular dystrophy.

Genes

SGCA Alpha-sarcoglycan is a protein that in humans is encoded by the ''SGCA'' gene. Function The dystrophin-glycoprotein complex (DGC) comprises a group of proteins that are critical to the stability of muscle fiber membranes and to the linking of ...

SGCB Beta-sarcoglycan is a protein that in humans is encoded by the ''SGCB'' gene. The dystrophin-glycoprotein complex (DGC) is a multisubunit protein complex that spans the sarcolemma and provides structural linkage between the subsarcolemmal cytoske ...

* SGCD * SGCE *

SGCG Gamma-sarcoglycan is a protein that in humans is encoded by the ''SGCG'' gene. The α to δ-sarcoglycans are expressed predominantly (β) or exclusively (α, γ and δ) in striated muscle. A mutation in any of the sarcoglycan genes may lead to ...

SGCZ Sarcoglycan zeta also known as SGCZ is a protein which in humans is encoded by the ''SGCZ'' gene. Function The zeta-sarcoglycan gene measures over 465 kb and localizes to 8p22. This protein is part of the sarcoglycan complex, a group of 6 p ...

References

Protein families {{protein-stub