O-methylation of L-dopa in melanin metabolism and the presence of catechol-O-methyltransferase in melanocytes.
Pigment Cell Res
; 7(6): 403-8, 1994 Dec.
Article
em En
| MEDLINE
| ID: mdl-7539130
ABSTRACT
O-Methylation of L-dopa was investigated as a possible regulatory mechanism in melanin metabolism. The methylation product of L-dopa, 3-O-methoxytyrosine was detected in extracts of cultured human melanocytes. The enzyme catechol-O-methyltransferase is responsible for this O-methylation and that of the dihydroxyindolic intermediates of melanogenesis. The enzyme is present in melanocytes in its soluble and membrane-bound isoforms. Immuno-electron microscopy suggests the presence of the membrane-bound enzyme in the endoplasmic reticulum. This localization may indicate a role of catechol-O-methyltransferase in protecting the melanocyte against reactive dihydroxyphenolic intermediates of melanogenesis leaking from the melanogenic compartments. On the other hand, the O-methylation of L-dopa may serve as a regulatory point in melanogenesis during early stage of tyrosinase processing in the endoplasmic reticulum.
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Base de dados:
MEDLINE
Assunto principal:
Levodopa
/
Catecol O-Metiltransferase
/
Isoenzimas
/
Melaninas
/
Melanócitos
Idioma:
En
Ano de publicação:
1994
Tipo de documento:
Article