Insertion of 1.1kb P-element in the 5' untranslated region, in the same transcriptional orientation as the y gene. The P-element is the same size, and is inserted in the same position as y76d28, but the P-element is in opposite orientation relative to the y gene in the two alleles.
Insertion of a P-element into y at +76bp (in the transcribed untranslated region). The P-element is inserted in the opposite orientation to that in y76d28.
P-element is completely replaced with a P-element, like that found in y76d28, oriented in the same direction as y transcription.