Family PHD

The prototypical Plant Homeodomain finger (PHD) was first identified in 1993 as a 'Cys4HisCys3' zinc finger motif in the homeodomain protein HAT3.1 in Arabidopsis thaliana. Since then, dozens of PHD fingers have been reported to express histone-binding activities. The present data support one notion that the histone H3 N-terminal segment, notably the 'NH2-ARTKQTARK' motif is virtually the major target for most histone-binding PHD fingers. On the other hand, as discussed below, the 'readership' of each particular PHD finger is deliberately 'twisted' to interpret the message encoded by different histone post-translational modifications within the flexible histone N-terminal tails. PHD family proteins have been shown to act as readers for many different histone post translational modifications (PMID:22194011).