Since our data show that the process of Gic1-septin cable formation does not necessarily require Cdc42-GTP, we propose that upon GAP-supported GTP hydrolysis, Cdc42-GDP, which has a much lower affinity to Gic1 than Cdc42-GTP, dissociates from the Gic1-septin complex and recruits more septin octamers to the bud site.
Surka and coworkers [38] described the immunoprecipitation of a complex containing septins 2, 6, 7 and 9 from HeLa cells, therefore suggesting that septin complexes may involve more than three components.
We describe here a Förster resonance energy transfer (FRET -based approach FRET -basedng in vitro the rapproachextent oforilameasuringatinn from septin complexes, binding of other proteins to septin structures, and the apparent affinities of these interactions.
SEPT2, SEPT7, and SEPT6/SEPT11 each represent a different septin group, suggesting that SEPT9 interacts with members of other groups to form a complex, and/or participates in the formation of previously unidentified septin complexes.
Furthermore, the extent to which other septin complexes, such as SEPT7-SEPT9-SEPT11 SEPT7-SEPT9-SEPT11 SEPT7-SEPT9-SEPT11 [17] or SEPT5-SEPT7-SEPT11 SEPT5-SEPT7-SEPT11 SEPT5-SEPT7-SEPT11 [18]EPT6-share compropertiest yet known.
(A ) Cdc42-GDP recruits septin complexes to the bud site.
Gic1 but not Cdc42-GDP binds to polymerization impaired septin complexes.
(A ) Representative EM image of negatively stained septin complexes incubated with Cdc42-GppNHp.
As a result, Cdc42 dissociates from the septin complexes, which in turn polymerize.
In order to evaluate the effect of Cdc42 on septin complexes, 0.1 μM of septin octamers and 0.5 μM of Gic1 were used.
