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Structural characterization of the catalytic ? and regulatory ? subunits of phosphorylase kinase in the context of the hexadecameric enzyme complex.

ABSTRACT: In the tightly regulated glycogenolysis cascade, the breakdown of glycogen to glucose-1-phosphate, phosphorylase kinase (PhK) plays a key role in regulating the activity of glycogen phosphorylase. PhK is a 1.3 MDa hexadecamer, with four copies each of four different subunits (?, ?, ? and ?), making the study of its structure challenging. Using hydrogen-deuterium exchange, we have analyzed the regulatory ? subunit and the catalytic ? subunit in the context of the intact non-activated PhK complex to study the structure of these subunits and identify regions of surface exposure. Our data suggest that within the non-activated complex the ? subunit assumes an activated conformation and are consistent with a previous docking model of the ? subunit within the cryoelectron microscopy envelope of PhK.

SUBMITTER: Rimmer MA

PROVIDER: S-EPMC5775173 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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Structural characterization of the catalytic γ and regulatory β subunits of phosphorylase kinase in the context of the hexadecameric enzyme complex.

Rimmer Mary Ashley MA Nadeau Owen W OW Artigues Antonio A Carlson Gerald M GM

Protein science : a publication of the Protein Society 20171121 2

In the tightly regulated glycogenolysis cascade, the breakdown of glycogen to glucose-1-phosphate, phosphorylase kinase (PhK) plays a key role in regulating the activity of glycogen phosphorylase. PhK is a 1.3 MDa hexadecamer, with four copies each of four different subunits (α, β, γ and δ), making the study of its structure challenging. Using hydrogen-deuterium exchange, we have analyzed the regulatory β subunit and the catalytic γ subunit in the context of the intact non-activated PhK complex ...[more]

PMID: 29098736

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