Expression of CRYP-alpha, LAR, PTP-delta, and PTP-rho in the developing Xenopus visual system.

Receptor protein tyrosine phosphatases (RPTPs), are involved in axon outgrowth and guidance not only in the Drosophila visual system (Garrity et al., 1999. Neuron 22, 707-717) but also in the developing vertebrate retina (Ledig et al., 1999a. J. Cell Biol. 147, 375-388). We have cloned a variety of Xenopus RPTPs, including four RPTPs expressed in the developing visual system (LAR, PTP-delta, CRYP-alpha and PTP-rho). These four RPTPs are transcribed in the developing optic vesicle during differentiation and in overlapping but distinct patterns in the developing retina during retinal layer formation. LAR, PTP-delta, and CRYP-alpha are also expressed in retinal ganglion cells during axonogenesis and during axon guidance from the retina to the optic tectum.