EXPRESSION OF THE RAT-BRAIN CREATINE TRANSPORTER IN-SITU AND IN TRANSFECTED HELA-CELLS

Using degenerate oligonucleotide probes encoding conserved regions of the gamma-aminobutyric acid/norepinephrine transporter gene family, we have cloned a rat brain cDNA encoding a creatine transporter (rCREAT) , rCREAT encodes a highly hydrophobic, 635-amino-acid protein possessi ng 12 potential transmembrane domains and canonical sites for N-linked glycosylation and protein phosphorylation, Transfection of rCREAT cDN A into mam malian cells results in the expression of [C-14]creatine up take, which is Phosphocreatine blocked by low micromolar concentration s of recognized creatine uptake inhibitors. Two rCREAT mRNAs are expre ssed in the rat brain, retina, kidney and heart, Whole-brain rCREAT mR NAs demonstrate a marked postnatal rise to steady-state adult levels, In situ hybridization studies indicate a widespread, differential rCRE AT mRNA expression in adult rat brain, with high expression noted over myelinated fiber tracts, cerebellar granule cells, hippocampal pyrami dal cells, brainstem nuclei and endothelial cells of the choroid plexu s, These studies will allow the development of new molecular probes us eful for defining the creatine transporter's cellular expression patte rn, function in ATP homeostasis and association with disorders of cell ular energy metabolism.