Hydroxyindole-O-methyltransferase in Y-79 human retinoblastoma cells: effect of cell attachment

Hydroxyindole-O-methyltransferase (HIOMT), the enzyme in the final step of melatonin synthesis, is present in the Y-79 human retinoblastoma cell line. Using electroblot immunolabellings, a single band corresponding to HIOMT was observed. Immunofluorescence, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and quantification of enzyme activity all revealed dramatic increases in HIOMT in cells attached to substrate compared to cells in suspension culture.