Eph Receptors and Ephrins Are Key Regulators of Morphogenesis 125
Table 1. Members of the Eph and ephrin families
New
Old
Oeneric
Human
Mouse
Rat
Chicken Xenopus a Zebrafish b
Receptors
EphAl
Eph
EphA2
Eck
Myk2,Sek2
042/0S0 rtk6
EphA3
Hek
Mek4
Tyro4
Cek4
rtk2
EphA4
Hek8
Sekl
Tyrol
Cek8
Pag
rtkl
EphAS
Hek7
Bsk
Ehkl, Rek7 Cek7
rtk7
EphA6
Ehk2
EphA7
Hekll
Mdkl, Ebk Ehk3
EphA8
Eek
Ptk4
Eek
rtk4/ZDK
EphBl
Net
Elk
Cek6
Xelk
EphB2
Erk, HekS, Drt
Nuk, Sek3 TyroS
CekS
rtk3
EphB3
Hek2
Sek4, MdkS Tyro6
CeklO
EphB4
Htk
Mykl, Mdk2
rtkS/8
EphBS
Cek9
EphB6
Mep
Ligands
ephrin-Al
Lerkl, B6l
L1
ephrin-A2
Elf!
Cek7-L
L3
ephrin-A3
Lerk3
Ehkl-L
ephrin-A4
Lerk4
ephrin-AS
Lerk7
All
Rags
L2/4
ephrin-Bl
Lerk2
Elk-L
CekS-L XLerk
ephrin-B2
LerkS, Htk-L
Elf-2
LS
ephrin-B3
Nlerk2
Elk-L3
Recognised nomenclature is on the left, original names for each member is given for
reference for the particular species concerned. (Based on Orioli and Klein 1997).
aOrthologous relationships of several Xenopus receptor and ephrin genes are still to be
resolved (Brandli and Kirschner 1995; Scales et al. 1995; Weinstein et al. 1996).
bTwo Xenopus or zebrafish receptors or ephrins separated by a dash represent probable
paialogues which exist due to genome duplication events.
proteins as they can bind to a receptor but fail to cluster and activate
them.
The formation of cell processes is fundamental to the movement of
cells and therefore to morphogenesis. Two well-studied examples of cell
process formation and cell movement in embryos are growth cone
extension from differentiating neurons and neural crest cell migration.
We outline below the evidence that Eph/ephrin signalling is an important component of the mechanisms underlying both events.