H1-alpha

Function

The H1-alpha gene codes for histone that interacts with euchromatin and is synthesized during the earliest stages of embryonic development (Chambers et al., 1987).

Protein

In the H1-alpha histone five contiguous repeats of the tetrapeptide SPBB (where B is R or K) occur between positions 10 and 29. Multiple seryl residues including SPBB are located in the NH2-, and BBSP in the COOH-end of the protein. They become phosphorylated by egg cytosol shortly after insemination (Porter et al., 1989).
The amino acid sequence of the first 34 residues of this histone shows striking similarity with sequences from three South African species.
The measurement of H1-alpha peptide elongation rate in cleaving embryos indicate an elongation rate (at 15 degrees C) of 0.80 codons per s. These values fall within the range of values of average peptide elongation rate for total protein in the cells (Goustin et al., 1982).

Subcellular location

Nuclear

Expression Pattern

H1-alpha is expressed at the earliest stages of embryonic development.
It is distributed to both daughter cells at mitosis, resulting in it being most concentrated in cells that stop dividing shortly after H1-alpha synthesis ends, while cells that continue to divide dilute their H1-alpha content in proportion to the number of cell divisions. Thus, H1-alpha becomes segregated in dividing cells (Pehrson et al., 1985).
H1-alpha histone was detected in all three cell types which comprise the 16-cell stage embryo: micromeres, macromeres, and mesomeres, but micromeres contain H1-alpha that migrates faster than that of macromeres and mesomeres (Chambers et al., 1987).