Primary structure of scombrine alpha: two different species with an
identical protamine.
Buesa C, del Valle L, Saperas N, Goethals M, Lloris D, Chiva M.
Flanders Interuniversity Institute of Biotechnology (UIB), Department of Biochemistry, Faculty of Medicine,
University of Gent, Belgium.
Abstract
We have studied the protamine scombrine alpha from the mackerel Scomber scombrus. Scombrine alpha
is found phosphorylated in spermatid nuclei, but not in nuclei of ripe sperm. It is a typical fish protamine,
made up of two distinct molecular species, each of 34 amino acid residues. The primary structure of the
main component of scombrine alpha is 100% identical to scombrine gamma, the nonmicroheterogeneous
protamine from Scomber australasicus (11). The second component of scombrine alpha is a very minor
molecular species that has an isoleucine instead of a valine in position 11. Nuclear sperm-specific basic
proteins display an enormous interspecific variability and it is very surprising that two different species
show identical protamines. In this work we suggest that evolutionary changes in primary structure of
protamines are restricted by several constitutive factors, especially when protamines either lack or have a
low degree of microheterogeneity.
Comp Biochem Physiol B Biochem Mol Biol. 1998 Jan;119(1):145-9.