Schematic diagram of exon 8 of protein 4.1R. Amino acid sequence at the 3′ end of exon 8 consisting of an AUGcodon surrounded by an optimal consensus Kozak sequence with a purine (G) in position −3 and a G in position +4. This is the first AUG codon downstream of AUG-2, which is in frame with the 4.1R coding sequence, therefore making it a good candidate codon for initiation of translation of the two isoforms lacking both AUG-1 and AUG-2.