The CAF-1 complex is a conserved heterotrimeric protein complex that promotes histone H3 and H4 deposition onto newly synthesized DNA during replication or DNA repair; specifically it facilitates replication-dependent nucleosome assembly with the major histone H3 (H3.1). This domain is an alpha helix which sits just upstream of the WD40 seven-bladed beta-propeller in the human RbAp46 protein. RbAp46 folds into the beta-propeller and binds histone H4 in a groove formed between this N-terminal helix and an extended loop inserted into blade six [1].

1: Structural basis for the recognition of histone H4 by the histone-chaperone RbAp46. Murzina NV, Pei XY, Zhang W, Sparkes M, Vicente-Garcia J, Pratap JV, McLaughlin SH, Ben-Shahar TR, Verreault A, Luisi BF, Laue ED; Structure. 2008;16:1077-1085. PMID:18571423