The histone variant H2AZ is incorporated preferentially at specific locations in 
chromatin to modulate chromosome functions. In Saccharomyces cerevisiae, 
deposition of histone H2AZ is mediated by the multiprotein SWR1 complex, which 
catalyzes ATP-dependent exchange of nucleosomal histone H2A for H2AZ. Here, we 
define interactions between SWR1 components and H2AZ, revealing a link between 
the ATPase domain of Swr1 and three subunits required for the binding of H2AZ. 
We discovered that Swc2 binds directly to and is essential for transfer of H2AZ. 
Swc6 and Arp6 are necessary for the association of Swc2 and for nucleosome 
binding, whereas other subunits, Swc5 and Yaf9, are required for H2AZ transfer 
but neither H2AZ nor nucleosome binding. Finally, the C-terminal alpha-helix of 
H2AZ is crucial for its recognition by SWR1. These findings provide insight on 
the initial events of histone exchange.