Javier Vargas Medrano - PKCbeta-dependent phosphorylation of the glycine transporter 1

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Vargas-Medrano, J., Castrejon, V., Ramirez, I. and Miranda-Arango, M. (2011). PKCbeta-dependent   phosphorylation of the glycine transporter 1.

Neurochem. Int.5(8):1123-1132.


  The extracellular levels of the neurotransmitter glycine in the   brain are tightly regulated by the glycine transporter 1 (GlyT1)   and the clearance rate for glycine depends on its rate of   transport and the levels of cell surface GlyT1. Over the years,   it has been shown that PKC tightly regulates the activity of   several neurotransmitter transporters. In the present work, by   stably expressing three N-terminus GlyT1 isoforms in porcine   aortic endothelial cells and assaying for [(32)P]-orthophosphate   metabolic labeling, we demonstrated that the isoforms GlyT1a,   GlyT1b, and GlyT1c were constitutively phosphorylated, and that   phosphorylation was dramatically enhanced, in a time dependent   fashion, after PKC activation by phorbol ester. The   phosphorylation was PKC-dependent, since pre-incubation of the   cells with bisindolylmaleimide I, a selective PKC inhibitor,   abolished the phorbol ester-induced phosphorylation. Blotting   with specific anti-phospho-tyrosine antibodies did not yield any   signal that could correspond to GlyT1 tyrosine phosphorylation,   suggesting that the phosphorylation occurs at serine and/or   threonine residues. In addition, a 23-40%-inhibition on V(max)   was obtained by incubation with phorbol ester without a   significant change on the apparent Km value. Furthermore,   pre-incubation of the cells with the selective PKCα/β inhibitor   Gö6976 abolished the downregulation effect of phorbol ester on   uptake and phosphorylation, whereas the selective PKCβ inhibitors   (PKCβ inhibitor or LY333531) prevented the phosphorylation   without affecting glycine uptake, defining a specific role of   classical PKC on GlyT1 uptake and phosphorylation. Taken   together, these data suggest that conventional PKCα/β regulates   the uptake of glycine, whereas PKCβ is responsible for GlyT1   phosphorylation.

  Address (URL): http://www.ncbi.nlm.nih.gov/pubmed?term=vargas%20medrano