Abstract. The Prevotella loescheii adhesin gene, plaA, contains a coding gap between a small open reading frame (ORF-1) and a large open reading frame (ORF-2). Translation of the plaA mRNA requires bypassing this 29-nt coding gap on the plaA transcript. We have determined the N-terminal peptide sequence of the SO34 adhesin beyond the gap sequence. This sequence shows that the peptide junction between ORF-1 and ORF-2 is continuous in the adhesin and supports the conclusion that synthesis of the SO34 adhesin occurs by a ribosomal hop mechanism. To elucidate upstream signals, we used the 5 RACE (rapid amplification of cDNA ends) technique to map the start point of the plaA mRNA. DNA sequencing of plasmids with the 5 RACE products placed the 5 end of plaA mRNA 270 nt upstream from the plaA start codon. A region corresponding to a Bacteroides fragilis promoter consensus sequence precedes this start site.