Patterns and putative regulatory mechanisms of high-affinity glutamate transporter expression by ruminants

J. C. Matthews, G. L. Sipe

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review


High-affinity, highly concentrative, L-glutamate uptake is integral to support nitrogen and carbon homeostasis of many cell-types and tissue-level metabolic "cycles". Given the physiological costs associated with forestomach fermentation (high ammonia loads and/or low dietary-derived carbohydrates), knowledge about how system XAG transport capacity is achieved and regulated is of particular interest to ruminant physiologists. Accordingly, this review discusses glutamate transport activities (systems); system XAG transport proteins; the importance of system XAG transport capacity in support of liver, white adipose, and striated muscle tissue function; identified and putative regulatory mechanisms that control system XAG transporter expression and function, including whole-body and tissue regulation, transcriptional regulation of GLT-1 expression, coordinated expression and function relationships between GLT-1 and glutamine synthetase, posttranscriptional regulation of EAAC1 functional capacity; and modulation of cattle carcass quality and expression of system XAG transporters and glutamine synthetase by chlortetracycline, a compositional-gain altering "antibiotic." Research that has characterized the patterns of system XAG transporter expression in sheep and/or cattle, and alteration of basal patterns to support altered metabolic demands in response to growth, physiological development under a typical commercial regimen, and alterations to finished cattle in response to subtherapeutic feeding of chlortetracycline are presented and the ramifications discussed.

Original languageEnglish
Title of host publicationRuminant Physiology
Subtitle of host publicationDigestion, Metabolism and Impact of Nutrition on Gene Expression, Immunology and Stress
Number of pages25
StatePublished - 2006


  • Beta-catenin
  • Gene expression
  • NF-kB
  • SLC1A1
  • SLC1A2

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences
  • General Engineering


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