2026-07-21T08:24:33Zhttps://repisalud.isciii.es/rest/oai/request
oai:repisalud.isciii.es:20.500.12105/261102025-12-18T12:56:57Zcom_20.500.12105_2052com_20.500.12105_2051col_20.500.12105_19609
Repisalud author Zarich-Dimitrievich, Natasha author Oliva-Martinez, Jose Luis author Jorge, Rocío author Santos, E author Rojas-Cabañeros, Jose Maria funder Instituto de Salud Carlos III funder Comunidad de Madrid (España) funder Ministerio de Educación y Ciencia (España) 2025-01-23T11:05:10Z 2025-01-23T11:05:10Z 2000-11-30 Zarich N, Oliva JL, Jorge R, Santos E, Rojas JM. The isoform-specific stretch of hSos1 defines a new Grb2-binding domain. Oncogene. 2000 Nov 30;19(51):5872-83. 10.1038/sj.onc.1203955 1476-5594 0950-9232 Oncogene 11127818 https://hdl.handle.net/20.500.12105/26110 hSos1 isoform II, defined by the presence of a 15 amino acid stretch in its carboxy-terminal region, exhibits higher Grb2 affinity than hSos1 isoform I. In this study, we investigated the cause for this difference and observed that, in addition to the four currently accepted Grb2-binding motifs, a number of additional, putative SH3-minimal binding sites (SH3-MBS) could be identified. The isoform II-specific 15 amino acid stretch contained one of them. Indeed, we demonstrated by site-directed mutagenesis that these SH3-MBS were responsible for the Grb2 interaction, and we found that C-terminal fragments of the two hSos1 isoforms (lacking the four cannonical Grb2-binding motifs, but containing the SH3-minimal binding sites) were able to bind Grb2, with the isoform II fragment showing higher Grb2 affinity than the corresponding isoform I fragment. Furthermore, we provide evidence that C-terminal truncated mutants of either hSos1 isoform, containing only the SH3-minimal binding sites, were able to originate in vivo stable complexes with Grb2. Although, Grb2-binding remains higher in both full-length isoforms, compared to the C-terminal truncated mutants, these mutants were also able to activate Ras, supporting a potential role of this C-terminal region as negative modulator of Sos1 activity. These findings document the existence of a new, functional, SH3-minimal binding site located in the specific stretch of hSos1 isoform II which may be responsible for the increased Grb2 affinity of this isoform in comparison to isoform I, and for the physiological properties differences between both isoforms. Moreover, these SH3-minimal binding sites may be sufficient to attain stable and functional hSosl-Grb2 complexes. eng hSos1 Isoforms Grb2 SH3 domains The isoform-specific stretch of hSos1 defines a new Grb2-binding domain. research article 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