Structure of the STRA6 receptor for retinol uptake.
Science
; 353(6302)2016 08 26.
Article
em En
| MEDLINE
| ID: mdl-27563101
ABSTRACT
Vitamin A homeostasis is critical to normal cellular function. Retinol-binding protein (RBP) is the sole specific carrier in the bloodstream for hydrophobic retinol, the main form in which vitamin A is transported. The integral membrane receptor STRA6 mediates cellular uptake of vitamin A by recognizing RBP-retinol to trigger release and internalization of retinol. We present the structure of zebrafish STRA6 determined to 3.9-angstrom resolution by single-particle cryo-electron microscopy. STRA6 has one intramembrane and nine transmembrane helices in an intricate dimeric assembly. Unexpectedly, calmodulin is bound tightly to STRA6 in a noncanonical arrangement. Residues involved with RBP binding map to an archlike structure that covers a deep lipophilic cleft. This cleft is open to the membrane, suggesting a possible mode for internalization of retinol through direct diffusion into the lipid bilayer.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Membrana Transportadoras
/
Vitamina A
/
Proteínas de Ligação ao Retinol
/
Proteínas de Peixe-Zebra
/
Proteínas de Membrana
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Science
Ano de publicação:
2016
Tipo de documento:
Article
País de afiliação:
Estados Unidos