THE HUMAN SON GENE - LARGE AND SMALL TRANSCRIPTS HAVE DIFFERENT 5'-TERMINAL SEQUENCES

Son gene cDNA clones were isolated earlier by hybridization screening of the human embryo cDNA clone library using gene K51 as a probe [1]. The nucleotide sequence of the human placenta small son gene transcrip t was determined. Four areas of complete tandem repeats (submitted for publication) have been revealed in its coding region. We have sequenc ed a fragment of a large son gene transcript 3.3 kbp long. The compari son of nucleotide sequences of two transcripts showed that they have d ifferent 5'-terminal segments and were probably formed by alternative splicing. The 5'-terminal region of the sequenced fragment contains tw o areas of complete tandem repeats not found in the small transcript. Results of analysis of this area support our model of son gene tandem repeats formation by duplication, mutation, and natural selection at t he protein level.