PMID- 10347209
OWN - NLM
STAT- MEDLINE
DCOM- 19990701
LR  - 20210209
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 23
DP  - 1999 Jun 4
TI  - Protein kinase C-beta activates tyrosinase by phosphorylating serine residues in 
      its cytoplasmic domain.
PG  - 16470-8
AB  - We have previously shown that protein kinase C-beta (PKC-beta) is required for
      activation of tyrosinase (Park, H. Y., Russakovsky, V., Ohno, S., and Gilchrest, 
      B. A. (1993) J. Biol. Chem. 268, 11742-11749), the rate-limiting enzyme in
      melanogenesis. We now examine its mechanism of activation in human melanocytes.
      In vivo phosphorylation experiments revealed that tyrosinase is phosphorylated
      through the PKC-dependent pathway and that introduction of PKC-beta into
      nonpigmented human melanoma cells lacking PKC-beta lead to the phosphorylation
      and activation of tyrosinase. Preincubation of intact melanosomes with purified
      active PKC-beta in vitro increased tyrosinase activity 3-fold. By immunoelectron 
      microscopy, PKC-beta but not PKC-alpha was closely associated with tyrosinase on 
      the outer surface of melanosomes. Western blot analysis confirmed the association
      of PKC-beta with melanosomes. Only the cytoplasmic (extra-melanosomal) domain of 
      tyrosinase, which contains two serines but no threonines, was phosphorylated by
      the serine/threonine kinase PKC-beta. These two serines at positions 505 and 509 
      both are present in the C-terminal peptide generated by trypsin digestion of
      tyrosinase. Co-migration experiments comparing synthetic peptide standards of all
      three possible phosphorylated tryptic peptides, a diphosphopeptide and two
      monophosphopeptides, to tyrosinase-phosphorylated in intact melanocytes by
      PKC-beta and then subjected to trypsin digestion revealed that both serine
      residues are phosphorylated by PKC-beta. We conclude that PKC-beta activates
      tyrosinase directly by phosphorylating serine residues at positions 505 and 509
      in the cytoplasmic domain of this melanosome-associated protein.
FAU - Park, H Y
AU  - Park HY
AD  - Department of Dermatology, Boston University School of Medicine, Boston,
      Massachusetts 02118, USA. hypark@acs.bu.edu
FAU - Perez, J M
AU  - Perez JM
FAU - Laursen, R
AU  - Laursen R
FAU - Hara, M
AU  - Hara M
FAU - Gilchrest, B A
AU  - Gilchrest BA
LA  - eng
GR  - R01 CA 72763/CA/NCI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Isoenzymes)
RN  - 452VLY9402 (Serine)
RN  - EC 1.14.18.1 (Monophenol Monooxygenase)
RN  - EC 2.7.11.13 (Protein Kinase C)
RN  - EC 2.7.11.13 (Protein Kinase C beta)
SB  - IM
MH  - Animals
MH  - Cells, Cultured
MH  - Cytoplasm/*metabolism
MH  - Humans
MH  - Isoenzymes/*metabolism
MH  - Melanosomes/enzymology
MH  - Monophenol Monooxygenase/*metabolism
MH  - Peptide Mapping
MH  - Phosphorylation
MH  - Protein Kinase C/*metabolism
MH  - Protein Kinase C beta
MH  - Rabbits
MH  - Serine/*metabolism
EDAT- 1999/05/29 00:00
MHDA- 1999/05/29 00:01
CRDT- 1999/05/29 00:00
PHST- 1999/05/29 00:00 [pubmed]
PHST- 1999/05/29 00:01 [medline]
PHST- 1999/05/29 00:00 [entrez]
AID - 10.1074/jbc.274.23.16470 [doi]
AID - S0021-9258(19)72994-9 [pii]
PST - ppublish
SO  - J Biol Chem. 1999 Jun 4;274(23):16470-8. doi: 10.1074/jbc.274.23.16470.