Robo Ig4 Is a Dimerization Domain.
J Mol Biol
; 429(23): 3606-3616, 2017 11 24.
Article
em En
| MEDLINE
| ID: mdl-29017837
ABSTRACT
Robo receptors play pivotal roles in axonal guidance as well as in neurogenesis, angiogenesis, cell migration, and cancer progression and invasiveness. They are considered to be attractive drug targets for the treatment of cancer, ocular neovascular disorders, chronic kidney diseases, and more. Despite their great importance, the mechanisms by which Robo receptors switch from their "off" to "on" states remain obscure. One possibility involves a monomer-to-dimer or dimer-to-monomer transition that facilitates the recruitment and activation of enzymatic effectors to instigate intracellular signaling. However, it is not known which domains mediate Robo dimerization, or the structural properties of the dimeric interactions. Here, we identify the extracellular Ig4 (D4) as a Robo dimerization domain. We have determined the crystal structure of the tandem Ig4-5 domains (D4-5) of human Robo2 and found that a hydrophobic surface on D4 mediates close homotypic contacts with a reciprocal D4. Analytical ultracentrifugation measurements of intact and mutated D4-5 shows that dimerization through the D4 interface is specific and has a dimerization dissociation constant of 16.9µM in solution. Direct fluorescence resonance energy transfer dimerization measurements in HEK293 cells corroborate the dimerization of transmembrane hRobo2 through D4, and a functional COS-7 cell collapse assay links D4-mediated dimerization with Robo intracellular signaling. The high level of conservation in the D4 dimerization interface throughout all Robo orthologs and paralogs implies that D4-mediated dimerization is a central hallmark in Robo activation and signaling.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Conformação Proteica
/
Receptores Imunológicos
/
Multimerização Proteica
Tipo de estudo:
Guideline
Limite:
Humans
Idioma:
En
Revista:
J Mol Biol
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Israel