Transfer of tyrosinase to melanosomes in Harding-Passey mouse melanoma

Archives of Biochemistry and Biophysics
Y TomitaM Seiji

Abstract

The transfer of tyrosinase from microsomes into melanosomes, without passing through the cytosol in the Harding-Passey mouse melanoma cell, was confirmed by experiments carried out using a combination of radioisotope tracer techniques and immunoprecipitation. 3H-Labeled amino acid incorporation into tyrosinase present in the microsome, melanosome, and soluble fractions confirmed the precursor-product relationship of the enzyme in the microsome fraction and in the melanosome fraction. However, two forms of the enzyme, Ts1- and Ts2-tyrosinase, separated from the soluble fraction by polyacrylamide gel electrophoresis, were shown to play no role in the transfer since little or no incorporation of radioactivity into tyrosinase in this fraction was found. It is suggested that most tyrosinase observed in the soluble fraction does not leak from the melanosomes or the microsomes during homogenization, but comes from necrotic tumor cells. It appears that melanosomal and microsomal tyrosinase might be released from the membrane of necrotic cells modified by various degradation enzymes, considering the data on the recovery of tyrosinase from the soluble fraction, where one-third of total enzyme activity in the postnuclear fraction could no...Continue Reading

References

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Citations

Jan 1, 1987·The International Journal of Biochemistry·V J Hearing, M Jiménez
Jun 1, 1988·Proceedings of the National Academy of Sciences of the United States of America·M JiménezV J Hearing
Mar 25, 1986·Nucleic Acids Research·S ShibaharaR Müller
May 29, 2013·Pigment Cell & Melanoma Research·Marco d'IschiaShosuke Ito
Feb 1, 1985·The Journal of Dermatology·Y TomitaM Seiji
Jan 1, 1988·Pigment Cell Research·J R JaraJ A Lozano
Jul 1, 1984·Archives of Biochemistry and Biophysics·G M Jacobsohn, M K Jacobsohn
Nov 1, 1985·The Journal of Investigative Dermatology·Y TomitaV J Hearing

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