Date of Award

Spring 2-28-2018

Document Type


Degree Name

Doctor of Philosophy (PhD)

First Advisor

Deborah S. Wuttke

Second Advisor

Joseph J. Falke

Third Advisor

Marcelo C. Sousa

Fourth Advisor

Michael R. Shirts

Fifth Advisor

Loren E. Hough


SH2 domains recognize phosphotyrosine (pY)-containing peptide ligands and regulate a wide array of signaling events within receptor tyrosine kinase pathways. SH2 domains have individualized specificity for peptides, encoded in the amino acids neighboring the pY of the ligand. In contrast to this simple view of signaling specificity, high-throughput array studies have identified several SH2 domains capable of recognizing peptides containing chemically distinct amino acids at the positions neighboring the pY. For example, the C-terminal SH2 domain (PLCC) of phospholipase C-γ1 (PLCγ1) typically binds peptides containing small and hydrophobic amino acids adjacent to the pY, but can also recognize unexpected peptides containing amino acids with polar or bulky side chains that deviate from this pattern. Similarly, the SH2 domain of Src homology 2 B adaptor protein 1 (SH2B1) can recognize peptides containing either hydrophobic or acidic amino acids at the +3 position C-terminal to the pY. This multimodal specificity may enable these proteins to participate in diverse, previously unrecognized, signaling pathways in response to binding chemically dissimilar partners and facilitate their ability to act as signaling hubs. To better understand this multimodal specificity, we have used thermodynamic and structural approaches, including isothermal titration calorimetry (ITC), nuclear magnetic resonance (NMR), and X-ray crystallography, to elucidate the mechanisms of diverse peptide binding to PLCC and SH2B1. We have identified hydrophobic and charged residues that play distinct roles in peptide binding to each SH2 domain. High resolution crystal structures of PLCC and SH2B1 have also identified conformational plasticity within the peptide ligands of PLCC and within several loops of SH2B1, which appears to contribute to the ability of these domains to recognize diverse ligands. A better understanding of the adaptability of PLCC and SH2B1 will expand the ability of researchers to identify biological ligands of SH2 domains, and will be necessary for the rational development of small molecule therapeutics to target, and selectively inhibit, a desired SH2 domain/ligand interface.