Shift in the isoelectric-point of milk proteins as a consequence of adaptive divergence between the milks of mammalian species.

ABSTRACT:

Background

Milk proteins are required to proceed through a variety of conditions of radically varying pH, which are not identical across mammalian digestive systems. We wished to investigate if the shifts in these requirements have resulted in marked changes in the isoelectric point and charge of milk proteins during evolution.

Results

We investigated nine major milk proteins in 13 mammals. In comparison with a group of orthologous non-milk proteins, we found that 3 proteins κ-casein, lactadherin, and muc1 have undergone the highest change in isoelectric point during evolution. The pattern of non-synonymous substitutions indicate that selection has played a role in the isoelectric point shift, since residues that show significant evidence of positive selection are much more

SUBMITTER: Khaldi N 

PROVIDER: S-EPMC3189186 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature