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Review
. 2018 May 11;293(19):7099-7107.
doi: 10.1074/jbc.R117.803023. Epub 2018 Feb 26.

The regulation of glycogenolysis in the brain

Owen W Nadeau  1 , Joseph D Fontes  1 , Gerald M Carlson  2
Affiliations
Review

The regulation of glycogenolysis in the brain

Owen W Nadeau et al. J Biol Chem. .

Abstract

The key regulatory enzymes of glycogenolysis are phosphorylase kinase, a hetero-oligomer with four different types of subunits, and glycogen phosphorylase, a homodimer. Both enzymes are activated by phosphorylation and small ligands, and both enzymes have distinct isoforms that are predominantly expressed in muscle, liver, or brain; however, whole-transcriptome high-throughput sequencing analyses show that in brain both of these enzymes are likely composed of subunit isoforms representing all three tissues. This Minireview examines the regulatory properties of the isoforms of these two enzymes expressed in the three tissues, focusing on their potential regulatory similarities and differences. Additionally, the activity, structure, and regulation of the remaining enzyme necessary for glycogenolysis, glycogen-debranching enzyme, are also reviewed.

Keywords: brain; energy metabolism; glycogen; neurobiology; phosphorylase.

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Conflict of interest statement

The authors declare that they have no conflicts of interest with the contents of this article

Figures

Figure 1.
Figure 1.
PhK structure and subunit locations. The cryo-EM reconstruction of the (αβγδ)4 mPhK complex (6) shows the relative locations of the four subunits within a single αβγδ protomer determined by immunoelectron microscopy or nanogold derivatization (3–5). The bridges between the octameric lobes are composed of β subunits (94). The lobe tips, which contain a C-terminal region of the α subunit (4), are separated by 176 Å (intralobal) and 213 Å (interlobal) (6).
Figure 2.
Figure 2.
N-terminal domains of βM and βB. Serines in red represent known PKA phosphorylation sites for βM (1, 37) and the putative PKA site for βB. The green residues in the βB sequence show the potential Pro-directed protein kinase phosphorylation sites.
See this image and copyright information in PMC

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