Figure 1.

Plasmid constructs. (A) Map of a region of pSPAnCOB. □, vector sequence; ▪, A. nidulans cobA gene exon; ▧, intron ORF; —, intron sequence. R = EcoRI, H = HindIII, P = PvuII, B = BglII Arrowheads, splice-sites. The upper dotted line denotes the region cloned into the expression vector pET28b. The lower dotted line denotes the region replaced by a SalI site to yield pCOBsal. (B) Amino-terminal amino acid sequence of the 32-kDa maturase protein expressed from pET28b. ∗, start of the Aspergillus sequence. (C) Map of a region of pCOBsal. The region shown corresponds precisely to the precursor used for all splicing assays. The number of bases in each segment are shown (the intron ORF remaining from pSPAnCOB is not shown as ▧). S = SalI.