LOCALIZATION AND FUNCTION OF TYROSINE-PHOSPHORYLATED PROTEIN IN PIG OOCYTES

Several proteins with phosphorylated tyrosine residues have been shown to be closely involved in the control of meiotic nuclear division. We identified a 42-kD protein in pig oocytes, using a polyclonal antibod y to a synthetic phosphotyrosine construct that increases significantl y in amount after 12 hr of maturation culture, and is discretely local ized to condensing and condensed chromosomes. However, since microinje ction of the antibody into oocytes blocks spindle formation, the role of this protein appears to be at that stage rather than directly in ch romosome condensation. Specificity of action of the 42-kD protein indi cates that it may be a phosphorylation-dependent component necessary f or successful spindle assembly. (C) 1996 Wiley-Liss, Inc.