Galphai generates multiple Pins activation states to link cortical polarity and spindle orientation in Drosophila neuroblasts.
Proc Natl Acad Sci U S A
; 104(36): 14306-11, 2007 Sep 04.
Article
em En
| MEDLINE
| ID: mdl-17726110
ABSTRACT
Drosophila neuroblasts divide asymmetrically by aligning their mitotic spindle with cortical cell polarity to generate distinct sibling cell types. Neuroblasts asymmetrically localize Galphai, Pins, and Mud proteins; Pins/Galphai direct cortical polarity, whereas Mud is required for spindle orientation. It is currently unknown how Galphai-Pins-Mud binding is regulated to link cortical polarity with spindle orientation. Here, we show that Pins forms a "closed" state via intramolecular GoLoco-tetratricopeptide repeat (TPR) interactions, which regulate Mud binding. Biochemical, genetic, and live imaging experiments show that Galphai binds to the first of three Pins GoLoco motifs to recruit Pins to the apical cortex without "opening" Pins or recruiting Mud. However, Galphai and Mud bind cooperatively to the Pins GoLocos 2/3 and tetratricopeptide repeat domains, respectively, thereby restricting Pins-Mud interaction to the apical cortex and fixing spindle orientation. We conclude that Pins has multiple activity states that generate cortical polarity and link it with mitotic spindle orientation.
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Base de dados:
MEDLINE
Assunto principal:
Blastômeros
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Polaridade Celular
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Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP
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Inibidores de Dissociação do Nucleotídeo Guanina
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Proteínas de Drosophila
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Drosophila melanogaster
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Fuso Acromático
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Neurônios
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article