A class of proteins that were originally identified by their ability to bind the DNA sequence CCAAT. The typical $CCAAT-$enhancer binding protein forms dimers and consists of an activation domain, a DNA-binding basic region, and a leucine-rich dimerization domain (LEUCINE ZIPPERS). CCAAT-BINDING FACTOR is structurally distinct type of $CCAAT-$enhancer binding protein consisting of a trimer of three different subunits.