Calcium dependent modification of distal C-terminal sequences of glycine transporter GlyT1

Glycine transporter GlyT1 plays important role in maintaining accurate glycine concentration in local brain microenvironment. Transporting efficiency of GlyT1 is strongly affected by the state of its distal C-terminus, which regulates transporter trafficking and cellular surface density. Using selected range of antibody epitopes against C-terminal region of GlyT1 we investigated its changes during calcium overload, the ubiquitous phenomena of several brain pathologies. We show that immunoreactivity against the last 12 amino acids of GlyT1C-terminal region exhibits robust calcium dependent decline, while the immunoreactivity of closely located region shows relatively small changes. Process is fully blocked by calcium chelation and inhibited by cysteine proteases inhibitors as well as inhibitors of protein kinase C. Distal GlyT1C-terminal end contains PDZ binding motif responsible for GlyT1 interaction with trafficking and clustering proteins. Its removal/modification could be part of the mechanism changing glycine homeostasis during physiological/pathological conditions characterized by elevated calcium.