Cloning of a gene encoding an antigen associated with the centrosome in Drosophila

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Abstract
The monoclonal antibody Bx63 recognizes a centrosomal antigen of Drosophila melanogaster by indirect immunofluorescence and identifies two proteins, with apparent molecular weights of 185 ×103 and 66×103, on Western blots. We have used this antibody to isolate five clones (λcsl, -2, -3, -4 and λj63) from λgtll expression libraries of Drosophila DNA. Using polyclonal anti-centro- somal sera raised against both immunoaffinity- purified Bx63 antigen and electrophoretically purified fusion protein from clone λcs3, we have demonstrated that the fusion proteins encoded by four of these clones (λcsl-4) share at least two epitopes with the 185×103Mr centrosomal antigen. This indicates that clones λcsl-4 contain DNA from the gene coding for this protein. The four clones are independent isolates from a single chromosomal site, which we show by in situ hybridization to correspond with salivary gland chromosome region 88E 4—8. A low-abundance transcript of approximately 4·0×103 bases corresponding to the cloned gene is detected in all stages of the Drosophila life-cycle.