title: The SAM domain inhibits EphA2 interactions in the plasma membrane.
abstract: All members of the Eph receptor family of tyrosine kinases contain a SAM domain near the C terminus, which has been proposed to play a role in receptor homotypic interactions and/or interactions with binding partners. The SAM domain of EphA2 is known to be important for receptor function, but its contribution to EphA2 lateral interactions in the plasma membrane has not been determined. Here we use a FRET-based approach to directly measure the effect of the SAM domain on the stability of EphA2 dimers on the cell surface in the absence of ligand binding. We also investigate the functional consequences of EphA2 SAM domain deletion. Surprisingly, we find that the EphA2 SAM domain inhibits receptor dimerization and decreases EphA2 tyrosine phosphorylation. This role is dramatically different from the role of the SAM domain of the related EphA3 receptor, which we previously found to stabilize EphA3 dimers and increase EphA3 tyrosine phosphorylation in cells in the absence of ligand. Thus, the EphA2 SAM domain likely contributes to a unique mode of EphA2 interaction that leads to distinct signaling outputs.
authors: Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218, United States.
authors: Deo R
authors: DR
authors: Singh
authors: Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218, United States.
authors: Fozia
authors: F
authors: Ahmed
authors: Program in Molecular Biophysics, Johns Hopkins University, 3400 Charles street, Baltimore, MD 21218, United States.
authors: Michael D
authors: MD
authors: Paul
authors: Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218, United States.
authors: Manasee
authors: M
authors: Gedam
authors: Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Road, La Jolla, San Diego, CA 92037, United States.
authors: Elena B
authors: EB
authors: Pasquale
authors: Department of Materials Science and Engineering, Johns Hopkins University, 3400 Charles Street, Baltimore, MD 21218, United States; Program in Molecular Biophysics, Johns Hopkins University, 3400 Charles street, Baltimore, MD 21218, United States. Electronic address: kh@jhu.edu.
authors: Kalina
authors: K
authors: Hristova
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002465:Cell Movement; D036382:Ephrin-A1 / Q000235:genetics / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D015870:Gene Expression; D057809:HEK293 Cells; D006801:Humans; D007700:Kinetics; D010766:Phosphorylation; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D036104:Receptor, EphA2 / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D000071682:Sterile Alpha Motif; D014443:Tyrosine / Q000378:metabolism
chemical_list: D036382:Ephrin-A1; D020033:Protein Isoforms; D011994:Recombinant Proteins; D014443:Tyrosine; D036104:Receptor, EphA2
keywords: EphA2; Interactions; Receptor tyrosine kinase; SAM domain