Structural insights into the Ca2+ and PI(4,5)P2 binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1.
Proc Natl Acad Sci U S A
; 110(51): 20503-8, 2013 Dec 17.
Article
em En
| MEDLINE
| ID: mdl-24302762
ABSTRACT
Proteins containing C2 domains are the sensors for Ca(2+) and PI(4,5)P2 in a myriad of secretory pathways. Here, the use of a free-mounting system has enabled us to capture an intermediate state of Ca(2+) binding to the C2A domain of rabphilin 3A that suggests a different mechanism of ion interaction. We have also determined the structure of this domain in complex with PI(4,5)P2 and IP3 at resolutions of 1.75 and 1.9 Å, respectively, unveiling that the polybasic cluster formed by strands ß3-ß4 is involved in the interaction with the phosphoinositides. A comparative study demonstrates that the C2A domain is highly specific for PI(4,5)P2/PI(3,4,5)P3, whereas the C2B domain cannot discriminate among any of the diphosphorylated forms. Structural comparisons between C2A domains of rabphilin 3A and synaptotagmin 1 indicated the presence of a key glutamic residue in the polybasic cluster of synaptotagmin 1 that abolishes the interaction with PI(4,5)P2. Together, these results provide a structural explanation for the ability of different C2 domains to pull plasma and vesicle membranes close together in a Ca(2+)-dependent manner and reveal how this family of proteins can use subtle structural changes to modulate their sensitivity and specificity to various cellular signals.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Cálcio
/
Fosfatidilinositol 4,5-Difosfato
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Proteínas de Transporte Vesicular
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Proteínas Adaptadoras de Transdução de Sinal
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Sinaptotagmina I
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Proteínas do Tecido Nervoso
Limite:
Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Espanha