The heterogeneity of human Gc-globulin.
Gc-globulin or group-specific component, also known as the vitamin D-binding protein, was investigated by the combined use of electrofocusing and immunofixation. Serum of the Gc 2-2 type was found to contain a single protein band whereas serum of the Gc 1-1 type shows two bands with a lower isoelectric point. The Gc 1-2 type contains all three bands known as Gc-2 (pI 5.10), Gc-1Slow (pI 5.03), and Gc-1Fast (pI 4.95). Each apoprotein shows an anodal shift of about 0.07 pH unit after incubation with an excess of 25-hydroxycholecalciferol. After treatment with sialidase Gc-1Fast focuses in the position of Gc-1Slow, whereas the position of Gc-2 remains unchanged.
D000510:Alpha-Globulins / Q000235:genetics / Q000302:isolation & purification; D002352:Carrier Proteins / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D009439:Neuraminidase; D010641:Phenotype; D014807:Vitamin D / Q000378:metabolism
D000510:Alpha-Globulins; D002352:Carrier Proteins; D014807:Vitamin D; D009439:Neuraminidase