Fig. 6. Determination of transcriptional start sites of the Manduca sexta V-ATPase genes mvB, mvG and mvd. The start sites were determined by RNase protection assays using 973 bp each of the 5' upstream regions as a template for in vitro transcription of ³²P-labelled ssRNA probes. After hybridization with poly(A) RNA, single-stranded RNA was digested with RNase A and T1. The remaining double-stranded RNA was separated on a denaturing polyacrylamide gel. Visualization of radioactively labelled bands was performed by exposing the gels to X-ray film. Nucleotide positions of identified transcriptional initiation sites that are similar to the consensus sequence KCABHYBY (Bucher, 1990) are shown on the right side of the figure.