Mitra G, Martin-Zanca D, Barbacid M
Developmental Oncology Section, Frederick Cancer Research Facility, MD 21701.
Proc Natl Acad Sci U S A. 1987 Oct;84(19):6707-11. doi: 10.1073/pnas.84.19.6707.
TRK is a human transforming gene generated in a colon carcinoma by a somatic rearrangement that fused a nonmuscle tropomyosin gene to sequences that shared extensive homology with members of the tyrosine-protein kinase supergene family. These sequences are likely to be derived from a transmembrane receptor gene whose putative ligand binding domain has been replaced by tropomyosin. In the present studies, we have expressed the entire coding sequences of the TRK oncogene as well as its protein kinase-related carboxyl-terminal domain in Escherichia coli. Antisera raised against these bacteria-synthesized TRK polypeptides has allowed us to identify the gene product of the TRK oncogene as a 70-kDa protein. Immunoprecipitates containing p70TRK have an associated protein kinase activity specific for tyrosine residues. Moreover, p70TRK is phosphorylated in vivo in serine (75%), threonine (20%), and tyrosine (5%) residues. Finally, immunofluorescence and cellular fractionation studies indicate that p70TRK is preferentially located in the cytoplasmic fraction.
TRK是一种人类转化基因，由结肠癌细胞中的体细胞重排产生，该重排将一个非肌肉原肌球蛋白基因与与酪氨酸蛋白激酶超基因家族成员具有广泛同源性的序列融合。这些序列可能源自一个跨膜受体基因，其假定的配体结合结构域已被原肌球蛋白取代。在本研究中，我们在大肠杆菌中表达了TRK癌基因的完整编码序列及其与蛋白激酶相关的羧基末端结构域。针对这些细菌合成的TRK多肽产生的抗血清使我们能够将TRK癌基因的基因产物鉴定为一种70 kDa的蛋白质。含有p70TRK的免疫沉淀物具有针对酪氨酸残基的相关蛋白激酶活性。此外，p70TRK在体内的丝氨酸（75%）、苏氨酸（20%）和酪氨酸（5%）残基上被磷酸化。最后，免疫荧光和细胞分级分离研究表明，p70TRK优先位于细胞质部分。
