Histone H1 diversity: bridging regulatory signals to linker histone function.

Genes encoding linker histone variants have evolved to link their expression to signals controlling the proliferative capacities of cells, i.e. cycling and growth-arrested cells express distinct and specific H1 subtypes. In metazoan, these variants show a tripartite structure, with considerably divergent sequences in their amino and carboxyl terminus domains. The aim of this review is to show how specific regulatory signals control the expression of an individual H1 and to discuss the functional significance of the two variables associated with a linker histone: its primary sequence and the timing of its expression.