Myophosphorylase

phosphorylase, glycogen; muscle (McArdle syndrome, glycogen storage disease type V)
Myophosphorylase^[1]
Identifiers
Symbol	PYGM
Entrez	5837
HUGO	9726
OMIM	608455
RefSeq	NM_005609
UniProt	P11217
Other data
EC number	2.4.1.1
Locus	Chr. 11 q12-q13.2

Myophosphorylase is the muscle isoform of the enzyme glycogen phosphorylase. This enzyme helps break down glycogen (a form of stored carbohydrate) into glucose-1-phosphate (not glucose), so that it can be utilized within the muscle cell.

Clinical significance

A deficiency is associated with Glycogen storage disease type V, also known as "McArdle's Syndrome".

A case study suggested that a deficiency in myophosphorylase may be linked with cognitive impairment. Besides muscle, this isoform is present in astrocytes, where it plays a key role in neural energy metabolism. A 55-year-old woman with McArdle disease has expressed cognitive impairment with bilateral dysfunction of prefrontal and frontal cortex. Further studies are needed to assess the validity of this claim.^[2]

References

↑ "RCSB Protein Data Bank - Structure Summary for 3MSC - Glycogen phosphorylase complexed with 2-nitrobenzaldehyde-4-(beta-D-glucopyranosyl)-thiosemicarbazone".
↑ Mancuso M, Orsucci D, Volterrani D, Siciliano G (March 2011). "Cognitive impairment and McArdle disease: Is there a link?". Neuromuscul Disord 21 (5): 356–8. doi:10.1016/j.nmd.2011.02.013. PMID 21382715.

External links

Myophosphorylase at the US National Library of Medicine Medical Subject Headings (MeSH)

Transferases: glycosyltransferases (EC 2.4)

2.4.1: Hexosyl-
transferases

Glucosyl-	Phosphorylase Starch Glycogen Myo- Glycogen synthase Debranching enzyme Branching enzyme 1,3-Beta-glucan synthase Ceramide glucosyltransferase

Galactosyl-	Lactose synthase B-N-acetylglucosaminyl-glycopeptide b-1,4-galactosyltransferase Glycoprotein-N-acetylgalactosamine 3-beta-galactosyltransferase (C1GALT1)

Glucuronosyl-	B3GAT1 B3GAT2 B3GAT3 UGT1A1 UGT1A3 UGT1A4 UGT1A5 UGT1A6 UGT1A7 UGT1A8 UGT1A9 UGT1A10 UGT2A1 UGT2A2 UGT2A3 UGT2B4 UGT2B7 UGT2B10 UGT2B11 UGT2B15 UGT2B17 UGT2B28 Hyaluronan synthase: HAS1 HAS2 HAS3

Fucosyl-	POFUT1 POFUT2 FUT1 FUT2 FUT3 FUT4 FUT5 FUT6 FUT7 FUT8 FUT9 FUT10 FUT11

Mannosyl-	Dolichyl-phosphate-mannose-protein mannosyltransferase POMT1 POMT2 DPM1 DPM3 ALG1 ALG2 ALG3 ALG6 ALG8 ALG9 ALG12

2.4.2: Pentosyl-
transferases

Ribose

ADP-ribosyltransferase	NAD⁺:diphthamide ADP-ribosyltransferase Diphtheria toxin NAD(P)⁺:arginine ADP-ribosyltransferase Pertussis toxin Cholera toxin Poly ADP ribose polymerase Sirtuin

Phosphoribosyltransferase	Adenine phosphoribosyltransferase Hypoxanthine-guanine phosphoribosyltransferase Uracil phosphoribosyltransferase Amidophosphoribosyltransferase

Other	Purine nucleoside phosphorylase: Thymidine phosphorylase ECGF1

Other

2.4.99: Sialyl
transferases

Proteins: enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases(list) EC2 Transferases(list) EC3 Hydrolases(list) EC4 Lyases(list) EC5 Isomerases(list) EC6 Ligases(list)

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