Deletion from 2332bp to 2345bp in the extracellular domain of the protein. This results in a deleted and frameshifted protein.
Mutation is a deletion leading to a frameshift and a premature stop codon. Position of mutation on reference sequence inferred by FlyBase curator based on author statement.
Embryos from heterozygous females are weakly ventralised at 29oC (50% of the embryos hatch into larvae, while the remainder do not undergo head involution and may not shorten the germ band), and moderately ventralised at 18oC. Females carrying TlDB1 in trans with a null allele of Tl produce dorsalised embryos.
Class II allele.