1Q47: Structure of the Semaphorin 3A Receptor-binding Module

Citation:
Abstract
The semaphorins are a large group of extracellular proteins involved in a variety of processes during development, including neuronal migration and axon guidance. Their distinctive feature is a conserved 500 amino acid semaphorin domain, a ligand-receptor interaction module also present in plexins and scatter-factor receptors. We report the crystal structure of a secreted 65 kDa form of Semaphorin-3A (Sema3A), containing the full semaphorin domain. Unexpectedly, the semaphorin fold is a variation of the beta propeller topology. Analysis of the Sema3A structure and structure-based mutagenesis data identify the neuropilin binding site and suggest a potential plexin interaction site. Based on the structure, we present a model for the initiation of semaphorin signaling and discuss potential similarities with the signaling mechanisms of other beta propeller cell surface receptors, such as integrins and the LDL receptor.
PDB ID: 1Q47Download
MMDB ID: 28525
PDB Deposition Date: 2003/8/1
Updated in MMDB: 2007/10 
Experimental Method:
x-ray diffraction
Resolution: 2.8  Å
Source Organism:
Similar Structures:
Biological Unit for 1Q47: dimeric; determined by author and by software (PISA)
Molecular Components in 1Q47
Label Count Molecule
Proteins (2 molecules)
2
Semaphorin 3A
Molecule annotation
Chemicals (4 molecules)
1
4
* Click molecule labels to explore molecular sequence information.

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