Multiple polyadenylation sites are active in the alpha 1-tubulin gene from Zea mays

Two cDNA clones (MR2 and MR29) encoding the same alpha-tubulin isotype (alpha 1) have been identified and characterized from maize roots. The sequence of these two cDNA clones is identical to a previously described cDNA clone (MR19) except in the location of their polyadenylation site. The sequence of the cDNA and its homologous genomic clone (MG19/14) shows two putative polyadenylation signals which could direct the variable 3' processing of the observed transcripts. Endonuclease S1 protection analysis in this 3' flanking region confirms the presence in the alpha 1-tubulin gene from Zea mays of these two main functional polyadenylation sites and possibly other related ones. The relative accumulation of RNAs bearing the two main polyadenylation sites has been tested by using a RNA-slot analysis of several tissues of the plant. It appears that a higher proportion of shorter mRNA species is found in actively dividing tissues.