Arabidopsis synaptotagmin SYT1, a type I signal-anchor protein, requires tandem C2 domains for delivery to the plasma membrane.
J Biol Chem
; 285(30): 23165-76, 2010 Jul 23.
Article
em En
| MEDLINE
| ID: mdl-20498364
ABSTRACT
The correct localization of integral membrane proteins to subcellular compartments is important for their functions. Synaptotagmin contains a single transmembrane domain that functions as a type I signal-anchor sequence in its N terminus and two calcium-binding domains (C(2)A and C(2)B) in its C terminus. Here, we demonstrate that the localization of an Arabidopsis synaptotagmin homolog, SYT1, to the plasma membrane (PM) is modulated by tandem C2 domains. An analysis of the roots of a transformant-expressing green fluorescent protein-tagged SYT1 driven by native SYT1 promoter suggested that SYT1 is synthesized in the endoplasmic reticulum, and then delivered to the PM via the exocytotic pathway. We transiently expressed a series of truncated proteins in protoplasts, and determined that tandem C(2)A-C(2)B domains were necessary for the localization of SYT1 to the PM. The PM localization of SYT1 was greatly reduced following mutation of the calcium-binding motifs of the C(2)B domain, based on sequence comparisons with other homologs, such as endomembrane-localized SYT5. The localization of SYT1 to the PM may have been required for the functional divergence that occurred in the molecular evolution of plant synaptotagmins.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Membrana Celular
/
Arabidopsis
/
Sinaptotagmina I
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article