Definition: In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.
Input:  In this study , a site of PDGF - induced tyrosine phosphorylation was mapped to Tyr 138 in the SH3 domain ; Tyr 138 is exposed on the SH3 peptide binding surface .
Output:
SH3 domain