DNA Binding of the Mouse Class II Major Histocompatibility CCAAT Factor Depends on Two Components

Abstract

A CCAAT-binding factor that recognizes a CCAAT sequence (Y box) located upstream of the major histocompatibility class II gene I-Aβ has been partially purified. This CCAAT-binding factor was found to consist of two components, designated factors A and B, both of which were required for efficient binding to the DNA. Factor A had an apparent molecular size of 34 kilodaltons, and factor B had an apparent molecular size of 42 to 46 kilodaltons.