A chemical called PMA blocks the creatine transporter in frog cells, and the more PMA they used or the longer they left it, the more it blocked the transporter, suggesting that activating protein kinase C can affect how the transporter works.

A chemical called 8-bromo-cyclic AMP, which activates protein kinase A, didn't change how well the creatine transporter worked in frog cells, suggesting that protein kinase A doesn't affect this transporter's activity.

When scientists put the human creatine transporter into frog cells, they found it needs sodium and chloride to move creatine into the cells, and it works best when there's about 20 millionths of a gram of creatine per milliliter of fluid.

A chemical called gamma-aminobutyric acid can block the creatine transporter in frog cells, but it takes about 6.5 thousandths of a gram per milliliter to block half of the transporter's activity, which is much less potent than other inhibitors tested.

When scientists changed one amino acid in the creatine transporter (from alanine to proline at position 285), it didn't change how well beta-guanidinopropionic acid, cyclocreatine, or gamma-guanidinobutyric acid could block the transporter in frog cells.