We have continued to characterize novel taxon-specific crystallins including eta-crystallin/aldehyde dehydrogenase in primitive placental mammals and mu-crystallin in marsupials. Both of these proteins appear to bind NAD(P) cofactors. We have also discovered that the alphaAins subunit of alpha-crystallin has a much more ancient origin than was expected; it is expressed in marsupials as well as in placental mammals. In an attempt to explain the anomalous subunit size of betaB1 in birds, we have found that this major cytoplasmic protein is specifically glycylated in normal bird lenses but not in mammals. At the same time, we noted that a minor fraction of alpha-crystallin subunits in both birds and mammals is modified with an O-linked GlcNAc moiety, something which may have functional significance for the alpha-crystallin/small heat-shock protein superfamily. In the analysis of the gene for tau-crystallin/alpha-enolase we have found that the gene promoter is highly active in lens explants and in cultured liver and skin cells. This suggests that the basis for any lens-preferred expression of this gene must lie in other cis elements or in posttranscriptional events. Alternatively the promoter may be responding to the stressed condition of the cultured cells in these experiments.
Showing the most recent 10 out of 17 publications
