Dynamics of the gp130 cytokine complex: a model for assembly on the cellular membrane.

Cytokines of the interleukin-6 (IL-6)-type family all bind to the glycoprotein gp130 on the cell surface and require interaction with two gp130 or one gp130 and another related signal transducing receptor subunit. In addition, some cytokines of this family, such as IL-6, interleukin-11, ciliary neurotrophic factor, neuropoietin, cardiotrophin-1, and cardiotrophin-1-like-cytokine, interact with specific ligand binding receptor proteins. High- and low-affinity binding sites have been determined for these cytokines.

Muscle glycogenosis with low phosphorylase kinase activity: mutations in PHKA1, PHKG1 or six other candidate genes explain only a minority of cases.

Muscle-specific deficiency of phosphorylase kinase (Phk) causes glycogen storage disease, clinically manifesting in exercise intolerance with early fatiguability, pain, cramps and occasionally myoglobinuria. In two patients and in a mouse mutant with muscle Phk deficiency, mutations were previously found in the muscle isoform of the Phk alpha subunit, encoded by the X-chromosomal PHKA1 gene (MIM # 311870). No mutations have been identified in the muscle isoform of the Phk gamma subunit (PHKG1).

Homozygous mutations in caveolin-3 cause a severe form of rippling muscle disease.

Heterozygous missense mutations in the caveolin-3 gene (CAV3) cause different muscle disorders. Most patients with CAV3 alterations present with rippling muscle disease (RMD) characterized by signs of increased muscle irritability without muscle weakness. In some patients, CAV3 mutations underlie the progressive limb-girdle muscular dystrophy type 1C (LGMD1C).