PMID- 18642117
OWN - NLM
STAT- MEDLINE
DCOM- 20090616
LR  - 20220408
IS  - 1573-4919 (Electronic)
IS  - 0300-8177 (Linking)
VI  - 319
IP  - 1-2
DP  - 2008 Dec
TI  - Skeletal muscle hexokinase: regulation in mammalian hibernation.
PG  - 41-50
LID - 10.1007/s11010-008-9875-5 [doi]
AB  - Skeletal muscle hexokinase (HK) from Richardson's ground squirrels was analyzed 
      to determine how the enzyme is regulated during hibernation, a state of cold 
      torpor. The HK II isozyme dominated in muscle and ~15% of total HK was bound to 
      the insoluble fraction. HK maximum activity was 33% lower in hibernator muscle 
      and the enzyme showed a significantly higher K ( m ) ATP (by 80%) and a lower K ( 
      i ) for glucose-6-P (by 40%) than euthermic HK (assayed at 22 degrees C). 
      However, 5 degrees C assay significantly reduced K ( m ) glucose of hibernator 
      HK. Stimulation of AMP-dependent protein kinase (AMPK) in hibernator extracts 
      elevated the HK activity and reduced K ( m ) ATP, but did not affect euthermic 
      HK. Stimulation of protein phosphatases significantly lowered the HK activity in 
      both situations. AMPK-dependent phosphorylation was confirmed by 
      immunopreciptiation of (32)P-labeled HK. DEAE-Sephadex ion exchange 
      chromatography revealed two peaks of HK in hibernator muscle extracts (low and 
      high phosphate forms), whereas only a single peak of phospho-HK was present in 
      euthermic muscle. We conclude that differential control of muscle HK in euthermic 
      versus hibernating states is derived from two main regulatory influences, 
      reversible protein phosphorylation and temperature effects on kinetic properties.
FAU - Abnous, Khalil
AU  - Abnous K
AD  - Institute of Biochemistry and Department of Chemistry, Carleton University, 
      Ottawa, ON, Canada.
FAU - Storey, Kenneth B
AU  - Storey KB
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20080720
PL  - Netherlands
TA  - Mol Cell Biochem
JT  - Molecular and cellular biochemistry
JID - 0364456
RN  - 56-73-5 (Glucose-6-Phosphate)
RN  - 8L70Q75FXE (Adenosine Triphosphate)
RN  - EC 2.7.1.1 (Hexokinase)
RN  - EC 2.7.11.31 (AMP-Activated Protein Kinases)
RN  - EC 3.1.3.16 (Phosphoprotein Phosphatases)
SB  - IM
MH  - AMP-Activated Protein Kinases/metabolism
MH  - Adenosine Triphosphate/metabolism
MH  - Animals
MH  - Glucose-6-Phosphate/metabolism
MH  - Hexokinase/*metabolism
MH  - Hibernation/*physiology
MH  - Muscle, Skeletal/*enzymology
MH  - Phosphoprotein Phosphatases/metabolism
MH  - Phosphorylation/physiology
MH  - Rodentia/*metabolism
EDAT- 2008/07/22 09:00
MHDA- 2009/06/17 09:00
CRDT- 2008/07/22 09:00
PHST- 2008/03/20 00:00 [received]
PHST- 2008/07/03 00:00 [accepted]
PHST- 2008/07/22 09:00 [pubmed]
PHST- 2009/06/17 09:00 [medline]
PHST- 2008/07/22 09:00 [entrez]
AID - 10.1007/s11010-008-9875-5 [doi]
PST - ppublish
SO  - Mol Cell Biochem. 2008 Dec;319(1-2):41-50. doi: 10.1007/s11010-008-9875-5. Epub 
      2008 Jul 20.