The Journal of Neuroscience, May 1, 2001, 21(9):3113-3125
A Novel Member of the Ig Superfamily,
turtle, is a CNS-Specific Protein Required for
Coordinated Motor Control
Kale D.
Bodily,
Clayton M.
Morrison,
Robert B.
Renden, and
Kendal
Broadie
Department of Biology, University of Utah, Salt Lake City, Utah
84112-0840
We describe here the cloning and functional characterization of a
neural-specific novel member of the Ig superfamily,
turtle (tutl), with a structure of five
Ig C2-type domains, two fibronectin type III domains, and one
transmembrane region. Alternative splicing of the tutl
gene produces at least four Tutl isoforms, including two transmembrane
proteins and two secreted proteins, with primary structures closely
related to a human brain protein (KIAA1355), the Deleted in Colorectal
Cancer/Neogenin/Frazzled receptor family, and the
Roundabout/Dutt1 receptor family. An allelic series of tutl gene mutations resulted in recessive lethality to
semilethality, indicating that the gene is essential. In contrast to
other family members, tutl does not play a detectable
role in axon pathfinding or nervous system morphogenesis. Likewise,
basal synaptic transmission and locomotory movement are unaffected.
However, tutl mutations cause striking movement defects
exhibited in specific types of highly coordinated behavior.
Specifically, tutl mutants display an abnormal response
to tactile stimulation, the inability to regain an upright position
from an inverted position (hence, "turtle"), and the inability to
fly in adulthood. These phenotypes demonstrate that tutl
plays an essential role in establishing a nervous system capable of
executing coordinated motor output in complex behaviors.
Key words:
Drosophila; Ig superfamily; coordination; motor control; behavior; cell adhesion; motor neuropathy
Copyright © 2001 Society for Neuroscience 0270-6474/01/2193113-13$05.00/0