Chromodomain

Part of speech: noun

Definitions

1. A protein structural module that recognizes and attaches to histones that have undergone specific chemical modifications
2. A conserved region of a protein capable of binding to histone proteins bearing particular post-translational modifications
3. A distinct protein region specialized in recognizing and interacting with chemically altered histone molecules

Etymology: Chromodomain is a plain technical coinage: "chromo-" from Ancient Greek "khrōma," meaning colour, and "domain," which English took from Old French "demaine," itself from Latin "dominium," ownership or lordship, rooted in "dominus," lord. The "domain" element carries the older sense of a realm or territory under a ruler's control, which is why it now names a distinct region of a molecule. In a chromodomain, the "chromo-" part does not refer to colour at all. The name comes from the protein's discovery in connection with chromosomes, the structures whose name also begins with "chromo-," because the stains that made chromosomes visible under the microscope were colour dyes. The term therefore links the Greek for colour to the idea of a chromosome-associated region, not to any visible hue.