In most species, Nuclear Factor Y (NF-Y) transcription factors are present. They usually composed three subunits: NF-YA/HAP2, NF-YB/HAP3, and NF-YC/HAP5. This group of TF has been implicated in diverse developmental process from animal to plant.
Plant NF-YB proteins have variable in length (e.g., 90?C240 amino acids in M. truncatula). They are characterized by a central domain that has structural and amino acid similarity with the histone fold motif (HFM) of the core histone H2B. This motif is composed of three alpha-helices separated by two beta strand-loop domains. It is involved in both protein?C DNA and protein?Cprotein interactions.

Reference:

1. T. Laloum, S. De Mita, P. Gamas, M. Baudin, A. Niebel, CCAAT-box binding transcription factors in plants: Y so many? Trends Plant Sci, (2012) 2. D. Dolfini, R. Gatta, R. Mantovani, NF-Y and the transcriptional activation of CCAAT promoters. Crit Rev Biochem Mol Biol 47, 29 (2012).

The family is the synonymous family of NF-YB in PlantTFDB.

The family is the subfamily family of CCAAT in PlnTFDB.