[Coding part of the son gene small transcript contains four areas of complete tandem repeats]

Overlapping cDNA clones for the smaller son gene transcript were isolated by several steps of human placenta cDNA library walking. Here we report the structure of repeats that exist at the long open reading, present in the structure of this smaller (5.6 kb) transcript of human gene son. We were able to identify in this transcript four areas of complete tandem repeats, formed by several steps of duplication. For three of them the extent of homology between amino acid sequences of repeated elements is higher than between their nucleic acid sequences. It means that amino acid sequences of repeated elements are conserved, that could reflect the structural significance for the function of hypothetical protein product of human gene son. On the basis of the results of analysis we proposed the model for the formation of repeats by processes of duplication, mutation and natural selection pressure at the expressed protein level.