Glycogenin

glycogenin glucosyltransferase
Glycogenin structure (from rabbit).[1]
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EC no.2.4.1.186
CAS no.117590-73-5
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Glycogenin is an enzyme involved in converting glucose to glycogen. It acts as a primer, by polymerizing the first few glucose molecules, after which other enzymes take over. It is a homodimer of 37-kDa subunits and is classified as a glycosyltransferase.

It catalyzes the chemical reactions:

UDP-alpha-D-glucose + glycogenin ⇌ UDP + alpha-D-glucosylglycogenin
UDP-alpha-D-glucose + a glucosyl-glycogenin ⇌ (1,4-alpha-D-glucosyl)n-glucosyl glucogenin + UDP + H+

Thus, the two substrates of this enzyme are UDP-alpha-D-glucose and glycogenin, whereas its two products are UDP and alpha-D-glucosylglycogenin.[2][3]

  1. ^ PDB: 1LL3​; Gibbons BJ, Roach PJ, Hurley TD (May 2002). "Crystal structure of the autocatalytic initiator of glycogen biosynthesis, glycogenin". J. Mol. Biol. 319 (2): 463–77. doi:10.1016/S0022-2836(02)00305-4. PMID 12051921.
  2. ^ Barengo R, Krisman CR (May 1978). "Initiation of glycogen biosynthesis in Escherichia coli. Studies of the properties of the enzymes involved". Biochimica et Biophysica Acta (BBA) - General Subjects. 540 (2): 190–6. doi:10.1016/0304-4165(78)90131-9. PMID 418819.
  3. ^ Butler NA, Lee EY, Whelan WJ (May 1977). "A protein-bound glycogen component of rat liver". Carbohydrate Research. 55: 73–82. doi:10.1016/s0008-6215(00)84444-4. PMID 861979.

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