Histone variants: are they functionally heterogeneous?

Table 2 Linker histone variants with potential unique functions

Variant	Organism	Essential for	Proposed function
		viability?
H1A	Xenopus	Not known	Specific gene repression during
			development
H1t	Mouse	No	Promotion of open chromatin
			structure; recombination during
			spermatogenesis
H1⁰	Mouse	No	Repression of gene expression;
			stabilization of chromatin
			structure during differentiation
H1c	Mouse	No	Activation of gene expression
H1^S-2,	Human	No	Activation of gene expression;
H1^S-4			selective depletion from active
			genes

ISSN: 1474-760X