Correlation between loss of middle ear bones and altered goosecoid gene expression in the branchial region following retinoic acid treatment of mouse embryos in vivo

Various methods are now available to identify the molecular partners of the component of a signal transduction pathway. Some interactions, however, can be technically difficult to detect because they depend upon transient tyrosine phosphorylation. Here, we present a simple affinity chromatography approach based on synthetic phosphopeptides to purify potential partners of phosphotyrosine-containing proteins. With this approach, we confirm the previously characterized interaction between Grb2 and the EGF receptor, and we identify novel partners of the IGF-1 receptor and of the JAK proteins. Methenyltetrahydrofolate synthetase (MTHFS) was identified as a potential mediator of IGF-1R dependent transformation. P85alpha, the regulatory subunit of PI3 kinase, was identified as one of four proteins recruited by a phosphopeptide mimicking a motif conserved in all JAK family members.