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Phosphorylation of glycolytic and gluconeogenic enzymes by the insulin receptor kinase
Author(s) -
Sale Elizabeth M.,
White Morris F.,
Kahn C. Ronald
Publication year - 1987
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240330103
Subject(s) - glycolysis , insulin receptor , phosphorylation , enzyme , insulin , microbiology and biotechnology , chemistry , biochemistry , biology , endocrinology , insulin resistance
Various glycolytic and gluconeogenic enzymes were tested as substrates for the insulin receptor kinase. Phosphofructokinase and phosphoglycerate mutase were found to be the best substrates. Phosphorylation of these enzymes was rapid, stimulated 2‐ to 6‐fold by 10 −7 M insulin and occurred exclusively on tyrosine residues. Enolase, fructose 1,6‐bisphosphatase, lactate dehydrogenases in decreasing order, were also subject to insulin‐stimulated phosphorylation but to a smaller extent than that for phpsphofructokinase or phosphoglycerate mutase. The phosphorylation of phosphofructokinase was studied most extensively since phosphofructokinase is known to catalyze a rate‐limiting step in glycolosis. The apparent Km of the insulin receptor for phosphofructokinase was 0.1 μM, which is within the physiologic range of concentration of this enzyme in most cells. Tyrosine phosphorylation of phosphofructokinase paralleled autophosphorylation of the β‐subunit of the insulin receptor with respect to time course, insulin dose response (half maximal effect between 10 −9 and 10 −8 M insulin), and cation requirement (Mn 2+ > Mg 2+ > > Ca 2+ ). Further study will be required to determine whether the tyrosine phosphorylation of phosphofructokinase plays a role in insulin‐stimulated increases in glycolytic flux.