J. Biol. Chem., Vol. 261, Issue 23, 10582-10586, 08, 1986
Purification to apparent homogeneity of the mating pheromone of mat-1 homozygous Euplotes raikovi
A Concetti, S Raffioni, C Miceli, D Barra and P Luporini
Mating type-specific mating pheromones autonomously released into the
environment control cell-cell union in conjugation of the marine ciliate
Euplotes raikovi. The mating pheromone, termed euplomone r-1, of cells of
the homozygous mating type determined by the mat-1/mat-1 genotype was
purified by means of a three-stage purification procedure which provides a
yield of 79%. Starting from 10 liters of supernatant, 3.3 mg of euplomone
r-1 were regularly recovered. Euplomone r-1 was identified with a protein
showing a molecular weight of 12,000, an isoelectric point of 3.7, and
unusually high contents of cysteine (15%) and tyrosine (5.8%). It appeared
active at a concentration of 3.4 +/- 0.5 X 10(-12) M. Carbohydrate and a
small colored compound, not yet identified, occurred in association with
partially purified euplomone r- 1 samples, whereas they were not detected
in samples of the final product of purification. An acidic shift was
apparently capable of destroying the carbohydrate/euplomone r-1
association, suggesting that it does not involve covalent bonds.
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