Glycogen priming

Lomako, J., Lomako, W.M., and Whelan, W.J. (1990) Substrate specificity of the autocatalytic protein that primes glycogen synthesis. FEBS Lett. 264 13-16. 

Glycogenin Primes the Initial Sugar Residues in Glycogen... 

Pitcher, J., Smythe, C., and Cohen, P. 1988. Glycogenin is the priming glucosyltransferase required for the initiation of glycogen biogenesis in rabbit skeletal muscle. Eur. J. Biochem. 176,391-395. 

C. Smythe and P. Cohen. 1991. The discovery of glycogenin and the priming mechanism for glycogen biogenesis Eur. J. Biochem. 200 625-631. (PubMed)... 

Phosphorylation of the (5 subunit activates the kinase and leads to glycogen degradation. Subsequent phosphorylation of the a subunit make the P subunit and the a subunit substrates for protein phosphatase. Thus, if the a subunit were modified before the P subunit, the enzyme would be primed for shutdown before it was activated and little glycogen degradation would take place. 

Carrier RNA (10 mg/mL tRNA) however, when random priming is performed then use glycogen as carrier (20 mg/mL stock solution). 

Methods of assay (m) = methylation (p) = periodate oxidation (e) = enzymic. B.V. = Blue Value (compare Refs. 3 and 4). Xmax = wavelength of maximum absorption of polysaccharide-iodine complex. Priming activity toward P-enzyme soluble starch = 1.0. Priming activity toward muscle phosphorylase glycogen = 100, corn amylopectin = 63. Molecular weight, 64,000 (compared with about 100,000 for the parent amylose). 

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