Lopez A J, Hogness D S
Department of Biochemistry, Stanford University School of Medicine, CA 94305-5307.
Proc Natl Acad Sci U S A. 1991 Nov 15;88(22):9924-8. doi: 10.1073/pnas.88.22.9924.
The homeotic gene Ultrabithorax (Ubx) specifies metameric identities in multiple tissues of the thorax and abdomen in Drosophila melanogaster. Alternatively spliced Ultrabithorax mRNAs encode five protein isoforms that differ in internal sequences immediately adjacent to a homeodomain DNA-binding motif. Each of these proteins is phosphorylated in vivo at multiple serine and threonine residues. An extensive panel of monoclonal antibodies was raised against the Ultrabithorax proteins, including antibodies specific for individual isoforms and antibodies that discriminated between different phosphorylation states. Characterization of these antibodies provided insights into shared and isoform-specific features of Ultrabithorax protein structure that may be functionally important. Immunohistochemical staining experiments demonstrated that each isoform is expressed in a different stage- and tissue-specific pattern and suggested that Ultrabithorax protein phosphorylation is also developmentally regulated. These results support the hypothesis that alternative splicing and phosphorylation modulate developmentally specific functions of the Ubx gene.
同源异型基因超双胸（Ubx）决定了黑腹果蝇胸部和腹部多个组织的体节特征。选择性剪接的超双胸mRNA编码五种蛋白质异构体，它们在紧邻同源结构域DNA结合基序的内部序列上有所不同。这些蛋白质中的每一种在体内多个丝氨酸和苏氨酸残基处都被磷酸化。针对超双胸蛋白产生了大量的单克隆抗体，包括针对单个异构体的特异性抗体以及区分不同磷酸化状态的抗体。对这些抗体的表征为超双胸蛋白结构的共同特征和异构体特异性特征提供了见解，这些特征可能在功能上很重要。免疫组织化学染色实验表明，每种异构体都以不同的阶段和组织特异性模式表达，并表明超双胸蛋白的磷酸化也受到发育调控。这些结果支持了选择性剪接和磷酸化调节Ubx基因发育特异性功能的假说。
