DLAR is a receptor-like, transmembrane protein-tyrosine phosphatase in
Drosophila that is expressed almost exclusively by developing neurons
. Analysis of Dlar loss-of-function mutations shows that DLAR plays a
key role during motoneuron growth cone guidance. Segmental nerve b (SN
b) motor axons normally exit the common motor pathway, enter the ventr
al target region, and then synapse on specific ventral muscles. In Dla
r mutant embryos, SNb axons bypass their normal target region and inst
ead continue to extend along the common pathway. SNd motor axons also
make pathfinding errors, while SNa and SNc axons appear normal. Thus,
DLAR controls the ability of certain motor axons to navigate specific
choice points in the developing Drosophila nervous system.