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.

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

1. ^ "RCSB Protein Data Bank - Structure Summary for 3MSC - Glycogen phosphorylase complexed with 2-nitrobenzaldehyde-4-(beta-D-glucopyranosyl)-thiosemicarbazone". http://www.rcsb.org/pdb/explore/explore.do?structureId=3MSC. 
2. ^ Mancuso M, Orsucci D, Volterrani D, Siciliano G (March 2011). "Cognitive impairment and McArdle disease: Is there a link?". Neuromuscul Disord. doi:10.1016/j.nmd.2011.02.013. PMID 21382715. 

External links

• MeSH Myophosphorylase

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	Xylosyltransferase · Arabinosyltransferase (Indolylacetylinositol arabinosyltransferase)

2.4.99: Sialyl
transferases

Beta-galactoside alpha-2,6-sialyltransferase · Monosialoganglioside sialyltransferase · ST8SIA4

B enzm: 1.1/2/3/4/5/6/7/8/10/11/13/14/15-18, 2.1/2/3/4/5/6/7/8, 2.7.10, 2.7.11-12, 3.1/2/3/4/5/6/7, 3.1.3.48, 3.4.21/22/23/24, 4.1/2/3/4/5/6, 5.1/2/3/4/99, 6.1-3/4/5-6