Premium
Association of AMP kinase β 2 subunit with glycogen particles as revealed by immunoelectron microscopy
Author(s) -
Bendayan Moise,
Londono Irene,
Gingras Diane,
Ruderman Neil,
Prentki Marc
Publication year - 2007
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.21.6.lb69
Subject(s) - immunoelectron microscopy , immunogold labelling , glycogen , endoplasmic reticulum , protein subunit , microbiology and biotechnology , immunolabeling , ampk , biology , protein kinase a , biochemistry , chemistry , kinase , ultrastructure , immunohistochemistry , anatomy , gene , immunology
AMP kinase β 2 subunit contains a functional glycogen binding domain (β‐GBD) that links AMPK to glycogen metabolism. By routine electron microscopy, glycogen deposits in cells are easily visualized as small rosettes of dark granules. However, immunocytochemistry requires weak fixation protocols that allow preservation of protein antigenicity but have the drawback of preventing retention of certain cellular elements such as glycogen. The cells thus appear vacuolated. Immunogold for AMPK subunits on such tissues leads to specific labelings located only in cytoplasmic areas surrounding the endoplasmic reticulum. We herein report the development of a new protocol for immunoelectron microscopy that retains glycogen deposits within the cells with the possibility of performing successfully the immunolabeling for the AMPK subunits. Upon applying specific antibodies against the various AMPK subunits on rat liver tissue, quantitative immunogold revealed that the labeling for the β 2 subunit is closely associated, for its very large majority, with the glycogen particles of the cell. The other subunits, α 1 and α 2 , are more abundant in cytoplasmic areas close to the endoplasmic reticulum and mitochondria. These results demonstrate the existence of a structural link between AMPK β 2 subunit and glycogen, a major energy store of the cell.