Hydroxyindole‐O‐Methyltransferase in Y‐79 Human Retinoblastoma Cells: Effect of Cell Attachment

Abstract
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 immunolabelings, 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.