A 3xTag:FLAG-Tag:StrepII-Venus-Tag:StrepII (FSVS) multi-tag cassette has been inserted into the endogenous sgg locus, at the C-terminal end of the open reading frame of the PA isoform (this protein isoform is identical to isoform PJ, and the tagged exon of the PA isoform is also shared by isoforms PR, PQ and PM).
Little or no tagged isoform sgg-PA expression is observed at early stages. By embryonic stage 9, strong and specific expression is seen in the developing CNS in the trunk and then the brain. As development proceeds, expression becomes prominent in the elaborating PNS and is particularly strong in the chordotonal organs, where it continues to the end of embryogenesis.