RGD Reference Report - Myocellular creatine and creatine transporter serine phosphorylation after starvation. - Rat Genome Database

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Myocellular creatine and creatine transporter serine phosphorylation after starvation.

Authors: Zhao, CR  Shang, L  Wang, W  Jacobs, DO 
Citation: Zhao CR, etal., J Surg Res 2002 Jun 1;105(1):10-6.
RGD ID: 1359082
Pubmed: PMID:12069495   (View Abstract at PubMed)
DOI: DOI:10.1006/jsre.2002.6431   (Journal Full-text)

BACKGROUND: Myocellular creatine, which is critically important for normal energy metabolism, increases in rat gastrocnemius muscle after starvation via unknown mechanisms. Creatine (Cr) uptake across plasma membranes is governed by a single, specific transporter (CrTr) that shares 50% amino acid sequence identity with GABA/choline/betaine transporters whose functions are modulated by phosphorylation. METHODS: Gastrocnemius muscle was collected from adult male Sprague-Dawley (225-250 g) rats that were randomized to receive normal rat chow and distilled water ad libitum (CTL) or distilled water alone for 4 days (STV). Total Cr, phosphocreatine (PCr), free Cr, and ATP were measured luminometrically. CrTr protein expression and protein serine and tyrosine phosphorylation and mRNA expression were determined using immunoprecipitation and quantitative Western blotting and reverse transcription polymerase chain reaction (RT-PCR) analyses, respectively. Guanidinoacetate methyltransferase (GAMT) activity, guanidinoacetic acid (GAA) content, creatine kinase (CK) activity, and creatinine (Crn) content were assayed luminometrically or spectrophotometrically. Creatine transporter uptake activity was also measured in skeletal muscle membrane vesicles. Data were analyzed by t test. RESULTS: Total Cr and free Cr increased 26 and 280% in STV (32.3 +/- 1.0 and 12.9 +/- 1.4 vs 25.7 +/- 1.1 and 3.4 +/- 0.9 micromol/g wet wt, mean +/- SEM, respectively, P < 0.01) whereas PCr content decreased 18% (18.6 +/- 0.8 vs 22.8 +/- 0.9 micromol/g wet wt, STV vs CTL P < 0.05). CrTr protein and mRNA expression, ATP, GAA, CK, GAMT, and protein tyrosine phosphorylation of CrTr were not significantly different between the two groups. However, protein serine phosphorylation of CrTr was significantly reduced by 30% (P < 0.05) and creatine uptake activity was significantly increased (P < 0.05) in starved animals. CONCLUSION: Increases in myocellular creatine content after starvation are associated with reduced serine phosphorylation of the creatine transporter.

Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process

Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Slc6a8Ratcreatine transmembrane transport  IDA  RGD 
CkmRatphosphocreatine biosynthetic process  IDA  RGD 

Molecular Function

Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
CkmRatcreatine kinase activity  IDA  RGD 
Slc6a8Ratcreatine:sodium symporter activity  IDA  RGD 
GamtRatguanidinoacetate N-methyltransferase activity  IDA  RGD 

Molecular Pathway Annotations    Click to see Annotation Detail View

RGD Manual Annotations

Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
CKMHumancreatine metabolic pathway  IDA  RGD 
CkmRatcreatine metabolic pathway  IDA  RGD 
GAMTHumancreatine metabolic pathway  ISS  RGD 
GamtRatcreatine metabolic pathway  IDA  RGD 
Slc6a8Ratcreatine metabolic pathway  IDA  RGD 
Objects Annotated

Genes (Rattus norvegicus)
Ckm  (creatine kinase, M-type)
Gamt  (guanidinoacetate N-methyltransferase)
Slc6a8  (solute carrier family 6 member 8)

Genes (Homo sapiens)
CKM  (creatine kinase, M-type)
GAMT  (guanidinoacetate N-methyltransferase)

Additional Information