ENTRY       EC 2.4.1.1
NAME        Phosphorylase
            Muscle phosphorylase a and b
            Amylophosphorylase
            Polyphosphorylase
CLASS       Transferases
            Glycosyltransferases
            Hexosyltransferases
SYSNAME     1,4-alpha-D-Glucan:orthophosphate alpha-D-glucosyltransferase
REACTION    (1,4-alpha-D-Glucosyl)n + Orthophosphate =
            (1,4-alpha-D-Glucosyl)n-1 + alpha-D-Glucose 1-phosphate
SUBSTRATE   (1,4-alpha-D-Glucosyl)n
            Orthophosphate
PRODUCT     (1,4-alpha-D-Glucosyl)n-1
            alpha-D-Glucose 1-phosphate
INHIBITOR   1,5-Gluconolactone
            Glucose
            Purine
COFACTOR    Pyridoxal phosphate
EFFECTOR    AMP
            IMP
            D-Glucose 6-phosphate
COMMENT     The recommended name should be qualified in each instance by
            adding the name of the natural substrate, e.g. maltodextrin
            phosphorylase, starch phosphorylase, glycogen phosphorylase.
            1,5-Gluconolactone is a very powerful reversible inhibitor of
            glycogen phosphorylase. Transition state analogue.
            Phosphorylase a and b are an active form (GPa) and inactive form
            (GPb).  From GPb to GPa is activated by AMP and IMP.
            Ser14 is phosphorylated by cAMP-activated protein kinase.
            Pyridoxal phosphate bound to Lys680 makes no mechnistic role, but
            a strucutral role.
            AMP and IMP are activator.  Glucose-6-phosphate is allosteric
            inhibitor.
            #STRUCTURE:
            Comparison of crystal strucutres of GPa and GPb are reported by
            Sprang, S.R.; et al. 1988, Nature, 336, 215-221.
            Glycogen phosphorylase is 842 a.a. and a dimer of two identical
            subunits.  Subunit is composed of two domains; domain 1 and 2.
            Domain 1: the regulatory domain (1-148).  Organized about a mostly
            parallel, nine stranded, beta-sheet core.  Two subdomains.
            Interface subdomain (1-315).  Glycogen-binding domain (316-484).
            Domain 2: contains a classical nucleotide-binding fold which is
            flanked by teo layers of helices.
            Catalytic site is located between domains 1 and 2.
            AMP: Tyr75 stack over the purine ring of AMP.  Arg309 and 310 form
            ion-pair hydrogen bonds with the phosphate group of AMP.
            Glucose-6-phosphate: the phosphate forms ion pairs with Arg309 and
            310.
PATHWAY     PATH: MAP00500  Starch and sucrose metabolism
DISEASE     MIM: 138550  Phosphorylase, glycogen, brain
            MIM: 232600  Phosphorylase, glycogen, muscle; McArdle disease (3)
            MIM: 232700  Phosphorylase, glycogen, liver; Glycogen storage
                         disease VI (1)
MOTIF       PS: PS00102  E-A-S-G-x-[GS]-N-M-K
GENES       ECO: b3417(malP) b3428(glgP)
            HIN: HI1361(glgP)
            BSU: glgP
            SYN: sll1356(glgP_1) slr1367(glgP_2)
            SCE: YPR160W(GPH1)
            HSA: PYGB(Hs.75658) PYGL(Hs.771) PYGM
STRUCTURES  PDB: 0PB1  0PPA  1ABB  1GPA  1GPB  1GPY  1NOI  1NOJ  1NOK  1PRI  
                 1PRJ  1PYG  1SKC  1SKD  1SKE  2GPB  3GPB  4GPB  5GPB  6GPB  
                 7GPB  8GPB  9GPB  
DBLINKS     University of Geneva ENZYME DATA BANK: 2.4.1.1
            WIT (What Is There) Metabolic Reconstruction: 2.4.1.1
            SCOP (Structural Classificaion of Proteins): 2.4.1.1
///