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. 2005 Apr 8;102(16):5697–5702. doi: 10.1073/pnas.0409824102

Fig. 1.

Fig. 1.

Replacement of maternally expressed histone B4 with somatic H1A during early Xenopus embryogenesis and linker histone assembly using NAP-1 as a chaperone. (A) Cytological sections of Xenopus embryos at various developmental stages stained with B4 (red) and H1A (green) antibodies and DAPI. White arrows indicate nuclei. (Scale bar, 0.1 mm.) (B) Purified recombinant B4, H1A, and NAP-1 were analyzed by SDS/PAGE. M, molecular mass markers. (C) B4 and H1A form complexes with NAP-1 at 1:1 stoichiometry (dots). Molar ratios of NAP-1 to linker histones are indicated at top of the native riboflavin-photopolymerized gel. Arrowheads, positions of NAP-1. LDH, lactate dehydrogenase. (D) NAP-1 functions as a chaperone for linker histone H1A. Reconstituted dinucleosomes (4 nM) were incubated with H1A or H1A/NAP-1 complex and analyzed by agarose gel electrophoresis. Free DNA, dinucleosomes, and one and two molecules of H1A per dinucleosome are indicated. (E) The assembled chromatin template does not contain NAP-1. The mixture of dinucleosomes and H1A/NAP-1 complex was separated on a sucrose gradient. Each fraction was analyzed by agarose gel electrophoresis (Upper) and immunoblotted with NAP-1 antibody (Lower).