DAG1

This gene encodes dystroglycan, a central component of dystrophin-glycoprotein complex that links the extracellular matrix and the cytoskeleton in the skeletal muscle. The encoded preproprotein undergoes O- and N-glycosylation, and proteolytic processing to generate alpha and beta subunits. Certain mutations in this gene are known to cause distinct forms of muscular dystrophy. Alternative splicing results in multiple transcript variants, all encoding the same protein. [provided by RefSeq, Nov 2015]

Dystroglycan 1

The dystroglycan complex is involved in a number of processes including laminin and basement membrane assembly, sarcolemmal stability, cell survival, peripheral nerve myelination, nodal structure, cell migration, and epithelial polarization.

Alpha-dystroglycan:
Extracellular peripheral glycoprotein that acts as a receptor for extracellular matrix proteins containing laminin-G domains. Receptor for laminin-2 (LAMA2) and agrin in peripheral nerve Schwann cells. Also acts as a receptor for laminin LAMA5 (By similarity).

Beta-dystroglycan:
Transmembrane protein that plays important roles in connecting the extracellular matrix to the cytoskeleton. Acts as a cell adhesion receptor in both muscle and non-muscle tissues. Receptor for both DMD and UTRN and, through these interactions, scaffolds axin to the cytoskeleton. Also functions in cell adhesion-mediated signaling and implicated in cell polarity.

Alpha-dystroglycan:
(Microbial infection) Acts as a receptor for lassa virus and lymphocytic choriomeningitis virus glycoprotein and class C new-world arenaviruses (PubMed:16254364, PubMed:19324387, PubMed:17360738).

Acts as a Schwann cell receptor for Mycobacterium leprae, the causative organism of leprosy, but only in the presence of the G-domain of LAMA2 (PubMed:9851927).

Aging Source: Ensembl
Angiogenesis involved in wound healing Source: Ensembl
Axon guidance Source: GO_Central
Axon regeneration Source: Ensembl
Basement membrane organization Source: Ensembl
Branching involved in salivary gland morphogenesis Source: Ensembl
Calcium-dependent cell-matrix adhesion Source: Ensembl
Cellular response to cholesterol Source: Ensembl
Cellular response to mechanical stimulus Source: Ensembl
Commissural neuron axon guidance Source: Ensembl
Epithelial tube branching involved in lung morphogenesis Source: Ensembl
Extracellular matrix organization Source: Reactome
Membrane protein ectodomain proteolysis Source: UniProtKB
Microtubule anchoring Source: UniProtKB
Modulation by virus of host process Source: UniProtKB
Morphogenesis of an epithelial sheet Source: Ensembl
Morphogenesis of an epithelium Source: GO_Central
Muscle attachment Source: GO_Central
Myelination in peripheral nervous system Source: Ensembl
Negative regulation of cell migration Source: UniProtKB
Negative regulation of MAPK cascade Source: UniProtKB
Negative regulation of protein kinase B signaling Source: UniProtKB
Nerve development Source: GO_Central
Nerve maturation Source: Ensembl
Positive regulation of basement membrane assembly involved in embryonic body morphogenesis Source: UniProtKB
Positive regulation of cell-matrix adhesion Source: Ensembl
Positive regulation of myelination Source: Ensembl
Positive regulation of oligodendrocyte differentiation Source: Ensembl
Positive regulation of protein kinase activity Source: Ensembl
Regulation of embryonic cell shape Source: UniProtKB
Regulation of epithelial to mesenchymal transition Source: UniProtKB
Regulation of gastrulation Source: UniProtKB
Regulation of neurotransmitter receptor localization to postsynaptic specialization membrane Source: Ensembl
Regulation of synapse organization Source: Ensembl
Response to denervation involved in regulation of muscle adaptation Source: Ensembl
Response to peptide hormone Source: Ensembl
Retrograde trans-synaptic signaling by trans-synaptic protein complex Source: Ensembl
Skeletal muscle tissue regeneration Source: Ensembl

Alpha-dystroglycan: Extracellular space
Beta-dystroglycan:
Nucleoplasm; Cytoskeleton; Cell membrane; Sarcolemma; Postsynaptic cell membrane. The monomeric form translocates to the nucleus via the action of importins and depends on RAN. Nuclear transport is inhibited by Tyr-892 phosphorylation. In skeletal muscle, this phosphorylated form locates to a vesicular internal membrane compartment. In muscle cells, sarcolemma localization requires the presence of ANK2, while localization to costameres requires the presence of ANK3. Localizes to neuromuscular junctions (NMJs) in the presence of ANK2 (By similarity). In peripheral nerves, localizes to the Schwann cell membrane. Colocalizes with ERM proteins in Schwann-cell microvilli.

Muscular dystrophy-dystroglycanopathy limb-girdle C9 (MDDGC9):
The disease is caused by variants affecting the gene represented in this entry. MDDGC7 is caused by DAG1 mutations that interfere with normal post-translational processing, resulting in defective DAG1 glycosylation and impaired interactions with extracellular-matrix components. Other muscular dystrophy-dystroglycanopathies are caused by defects in enzymes involved in protein O-glycosylation. An autosomal recessive muscular dystrophy showing onset in early childhood, and associated with mental retardation without structural brain anomalies.
Muscular dystrophy-dystroglycanopathy congenital with brain and eye anomalies A9 (MDDGA9):
An autosomal recessive disorder characterized by congenital muscular dystrophy associated with cobblestone lissencephaly and other brain anomalies, eye malformations, profound mental retardation, and death usually in the first years of life. Included diseases are the more severe Walker-Warburg syndrome and the slightly less severe muscle-eye-brain disease.

Extracellular: 654-749
Helical: 750-775
Cytoplasmic: 776-895

Alpha-dystroglycan:
O-glycosylated. POMGNT1 catalyzes the initial addition of N-acetylglucosamine, giving rise to the GlcNAc(beta1-2)Man(alpha1-)O-Ser/Thr moiety and thus providing the necessary basis for the addition of further carbohydrate moieties (PubMed:27493216). Heavily O-glycosylated comprising of up to two thirds of its mass and the carbohydrate composition differs depending on tissue type. Mucin-type O-glycosylation is important for ligand binding activity. O-mannosylation is found in high abundance in both brain and muscle where the most abundant glycan is Sia-alpha-2-3-Gal-beta-1-4-Glc-NAc-beta-1-2-Man. In muscle, glycosylation on Thr-317, Thr-319 and Thr-379 by a phosphorylated O-mannosyl glycan with the structure 2-(N-acetylamido)-2-deoxygalactosyl-beta-1,3-2-(N-acetylamido)-2-deoxyglucosyl-beta-1,4-6-phosphomannose is mediated by like-acetylglucosaminyltransferase (LARGE1) protein and is required for laminin binding (PubMed:20044576, PubMed:21987822, PubMed:24256719). The O-glycosyl hexose on Thr-367, Thr-369, Thr-372, Thr-381 and Thr-388 is probably mannose. O-glycosylated in the N-terminal region with a core 1 or possibly core 8 glycan. The brain form displays a unique glycosylation pattern which is absent in other tissues; this form shows enhanced binding to laminin LAMA5 compared to the skeletal muscle form (By similarity).By similarity11 Publications
Alpha-dystroglycan:
(Microbial infection) O-mannosylation is required for binding lymphocytic choriomeningitis virus, Old World Lassa fever virus, and clade C New World arenaviruses.
Beta-dystroglycan:
N-glycosylated.
Autolytic cleavage produces the alpha and beta subunits. In cutaneous cells, as well as in certain pathological conditions, shedding of beta-dystroglycan can occur releasing a peptide of about 30 kDa.
SRC-mediated phosphorylation of the PPXY motif of the beta subunit recruits SH2 domain-containing proteins, but inhibits binding to WWW domain-containing proteins, DMD and UTRN. This phosphorylation also inhibits nuclear entry.