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The C‐Terminus of α Subunit Determines The Catalytic Activity of AMP‐activated Protein Kinase
Author(s) -
Cui Xiaopei,
Gao Haiqing,
Hwang JennKang,
Shyy John YJ
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.473.3
Subject(s) - ampk , protein kinase a , protein subunit , amp activated protein kinase , microbiology and biotechnology , chemistry , phosphorylation , gamma subunit , kinase , acetyl coa carboxylase , biochemistry , biology , pyruvate carboxylase , enzyme , gene
Comprising a catalytic α subunit and two regulatory β and γ subunits, AMP‐activated protein kinase (AMPK) regulates cellular energy homeostasis as well as cell proliferation and polarity. To date, the mechanism underlying the autoregulation of AMPK kinase activity remains elusive. Using tissues collected from mice ablated with AMPKα, we showed that the stability of β subunit depended on the presence of α. In the absence of α1 or α2 subunit, the decrease in β was due to an accelerated protein degradation, which could be rescued by the α complementation. Similarly, siRNA knocking down of β decreased α expression in cultured cells. Experiments with α2 truncations revealed that residues 412–426 of murine α2 were critical for the binding of β subunit. Exhibited little effect on αβ interaction, a 12‐a.a truncation at the C‐terminal (aa. 541–552) of α2 resulted in decreased kinase activity. This truncation could act as a domain negative mutant to abate endogenous AMPK activity in phosphorylating the downstream targets such as acetyl‐CoA carboxylase and endothelial nitric oxide synthase. Computational simulation suggested a fluctuate structure of β in the newly formed αβ complex which would be responsible for the decreased kinase activity. Taken together, the interaction of αβ is important in maintaining the AMPK stability, whereas the C‐terminal tail of the α is necessary for the kinase activity of AMPK.