This is the first of two HU domains found in the CCDC81-like proteins. CCDC81 has been experimentally linked to the centrosome; eukaryotic CCDC81 HU domains are predicted to function in protein-protein interactions in centrosome organization and potentially contribute to cargo-binding in conjunction with Dynein-VII. A striking lineage-specific expansion of the domain is observed in birds, where the HU domains could function in recognition of non-self molecules [1].

1: Novel clades of the HU/IHF superfamily point to unexpected roles in the eukaryotic centrosome, chromosome partitioning, and biologic conflicts. Burroughs AM, Kaur G, Zhang D, Aravind L; Cell Cycle. 2017;16:1093-1103. PMID:28441108