Finan P M, Hall A, Kellie S
Yamanouchi Research Institute, Littlemore Hospital, Oxford, UK.
FEBS Lett. 1996 Jul 1;389(2):141-4. doi: 10.1016/0014-5793(96)00552-2.
The binding of proteins from an immortalised B-cell line to a panel of SH3 domains was investigated in vitro. One of the most prominent SH3 domain binding proteins was a 68 kD polypeptide which strongly associated with the SH3 domains of c-src, p85a and p47phox and weakly with the SH3 domain of PLCgamma and n-src with undetectable binding to the other SH3 domains tested. Immunoblotting identified this protein as human Sam68. The ability of proline-rich peptides homologous to the Sam68 primary sequence to inhibit the binding of Sam68 to SH3 domains was investigated. Only one peptide inhibited binding of Sam68 to the p85alpha SH3 domain, whereas several peptides inhibited binding of Sam68 to c-src SH3 domain, suggesting that Sam68 uses different proline-rich motifs to bind to different SH3 domains. A peptide derived from residues 32-44 of Sam68 which fits the class II SH3 domain binding consensus sequence inhibited binding of Sam68 to both p85alpha SH3 domain and c-src SH3 domain, but with differential potency, suggesting a differential affinity of these SH3 domains for this proline-rich motif.
在体外研究了来自永生化B细胞系的蛋白质与一组SH3结构域的结合情况。最显著的SH3结构域结合蛋白之一是一种68 kD的多肽，它与c-src、p85a和p47phox的SH3结构域强烈结合，与PLCγ的SH3结构域弱结合，与n-src的SH3结构域结合不可检测，而与测试的其他SH3结构域无结合。免疫印迹鉴定该蛋白为人Sam68。研究了与Sam68一级序列同源的富含脯氨酸的肽抑制Sam68与SH3结构域结合的能力。只有一种肽抑制Sam68与p85α SH3结构域的结合，而几种肽抑制Sam68与c-src SH3结构域的结合，这表明Sam68利用不同的富含脯氨酸的基序与不同的SH3结构域结合。源自Sam68第32 - 44位残基的一种肽符合II类SH3结构域结合共有序列，它抑制Sam68与p85α SH3结构域和c-src SH3结构域的结合，但效力不同，这表明这些SH3结构域对该富含脯氨酸的基序具有不同的亲和力。
