1F0M

MONOMERIC STRUCTURE OF THE HUMAN EPHB2 SAM (STERILE ALPHA MOTIF) DOMAIN

Summary for 1F0M

• Entry DOI: 10.2210/pdb1f0m/pdb
• Related: 1b4f
• Descriptor: EPHRIN TYPE-B RECEPTOR 2 (2 entities in total)
• Functional Keywords: sam domain, signaling protein
• Biological source: Homo sapiens (human)
• Cellular location: Cell membrane; Single-pass type I membrane protein: P29323
• Total number of polymer chains: 1
• Total formula weight: 9401.77

Authors

Thanos, C.D.,Faham, S.,Goodwill, K.E.,Cascio, D.,Phillips, M.,Bowie, J.U. (deposition date: 2000-05-16, release date: 2000-07-04, Last modification date: 2024-02-07)

Primary citation

Thanos, C.D.,Faham, S.,Goodwill, K.E.,Cascio, D.,Phillips, M.,Bowie, J.U.
Monomeric structure of the human EphB2 sterile alpha motif domain.
J.Biol.Chem., 274:37301-37306, 1999

PubMed Abstract: The sterile alpha motif (SAM) domain is a protein module found in many diverse signaling proteins. SAM domains in some systems have been shown to self-associate. Previous crystal structures of an EphA4-SAM domain dimer (Stapleton, D., Balan, I., Pawson, T., and Sicheri, F. (1999) Nat. Struct. Biol. 6, 44-49) and a possible EphB2-SAM oligomer (Thanos, C. D., Goodwill, K. E., and Bowie, J. U. (1999) Science 283, 833-836) both revealed large interfaces comprising an exchange of N-terminal peptide arms. Within the arm, a conserved hydrophobic residue (Tyr-8 in the EphB2-SAM structure or Phe-910 in the EphA4-SAM structure) is anchored into a hydrophobic cleft on a neighboring molecule. Here we have solved a new crystal form of the human EphB2-SAM domain that has the same overall SAM domain fold yet has no substantial intermolecular contacts. In the new structure, the N-terminal peptide arm of the EphB2-SAM domain protrudes out from the core of the molecule, leaving both the arm (including Tyr-8) and the hydrophobic cleft solvent-exposed. To verify that Tyr-8 is solvent-exposed in solution, we made a Tyr-8 to Ala-8 mutation and found that the EphB2-SAM domain structure and stability were only slightly altered. These results suggest that Tyr-8 is not part of the hydrophobic core of the EphB2-SAM domain and is conserved for functional reasons. Cystallographic evidence suggests a possible role for the N-terminal arm in oligomerization. In the absence of a direct demonstration of biological relevance, however, the functional role of the N-terminal arm remains an open question.

PubMed: 10601296
DOI: 10.1074/jbc.274.52.37301

Experimental method

X-RAY DIFFRACTION (2.2 Å)