Conservation of the 3 '-untranslated region of the Rab1a gene in amniote vertebrates: exceptional structure in marsupials and possible role for posttranscriptional regulation

The YPT1/RAB1 protein, a key regulator of the intracellular vesicle transpo rt in eukaryotes, is highly conserved in function and amino acid sequence. Here we report that the most highly conserved nucleotide sequence of the Ra b1a gene of amniote vertebrates corresponds to the 3'-untranslated region ( 3'-UTR) of the mRNA. Sequences of 27 species ranging from mammals to saurop sida are >91% identical in this region. Secondary structure prediction proc edures applied to the 3'-UTR sequences between positions 750 and 984 and 14 28 (mouse cDNA: Y00094), respectively, of the RAB1a mRNAs revealed families of alternative structures around nucleotide position 800 as recurrent feat ures. The two hairpin loops are also predicted for marsupials, despite of t heir exceptional extension of the A-rich sequence in between. Yet, sequence conservation is much higher than required to conserve secondary structure. Implications for posttranscriptional regulation and protein binding are di scussed. (C) 2000 Federation of European Biochemical Societies, Published b y Elsevier Science B.V. All rights reserved.