14
G. Jansen et al.
ent pathways can be integrated. Knowledge of the function of all G
protein subunits of an organism can greatly increase our understanding
of these processes.
Several Ga subunit genes have been isolated from C. elegans by
peR, using degenerate oligonucleotide primers (Fino Silva and Plasterk
1990; Lochrie et al. 1991; Mendel et al. 1995; Brundage et al. 1996;
Park et al. 1997), or in forward genetic screens (Segalat et al. 1995;
Roayaie et al. 1998). Among these genes are homologues of three of the
four mammalian classes; Gj/Goa: goa-l (Mendel et al. 1995; Segalat et
al. 1995) and Gsa: gsa-l (Park et al. 1997). Functional analysis showed
that goa-l and gsa-l are expressed in many neurons and muscle cells,
and that mutation of these genes and egl-30 affects muscle activity (in
egg laying as well as locomotion) (Mendel et al. 1995; Segalat et al.
1995; Brundage et al. 1996; Korswagen et al. 1997).
In addition, four Ga genes have been identified that were not clear
members of the known mammalian G protein classes (Lochrie et al.
1991; Roayaie et al. 1998). Three of these new Ga genes, gpa-2, gpa-3,
and odr-3, were found to be expressed in a subset of the amphid
neurons, 12 pairs of sensory neurons in the head (Zwaal et al. 1997;
Roayaie et al. 1998). Further analysis of the three new Ga genes indeed
showed that they are involved in several different perception processes:
taste, olfaction, nociception, and dauer formation (Zwaal et al. 1997;
Roayaie et al. 1998).
Although most of the specificity of G protein function lies in the a
subunit, the ~y complex also has significant signaling capabilities. Until
recently only one ~ subunit gene was identified in C. elegans, gpb-l
(van der Voom et al. 1990). Inactivation of this gene leads to embryonic
lethality as a result of inappropriate orientation of the planes of cell
division (Zwaal et al. 1996). We recently found a second ~ subunit gene,
gpb-2, which does not seem to be required for viability (F Simmer, R
Korswagen, G Jansen, K Thijssen, and RHA Plasterk, unpublished
results). Thus far, two y subunit genes have been identified, gpc-l and 2
(G Jansen, K Thijssen, and RHA Plasterk, unpublished results). It
should be noted that the y subunit is small and not well conserved, so
that identification by sequence comparison is not trivial. Therefore, it is
likely that additional y subunit genes remain to be found.
The availability of the genomic sequence and the conservation of all
a subunits during evolution enabled us to identify all Ga genes. Re-
G. Jansen et al.
ent pathways can be integrated. Knowledge of the function of all G
protein subunits of an organism can greatly increase our understanding
of these processes.
Several Ga subunit genes have been isolated from C. elegans by
peR, using degenerate oligonucleotide primers (Fino Silva and Plasterk
1990; Lochrie et al. 1991; Mendel et al. 1995; Brundage et al. 1996;
Park et al. 1997), or in forward genetic screens (Segalat et al. 1995;
Roayaie et al. 1998). Among these genes are homologues of three of the
four mammalian classes; Gj/Goa: goa-l (Mendel et al. 1995; Segalat et
al. 1995) and Gsa: gsa-l (Park et al. 1997). Functional analysis showed
that goa-l and gsa-l are expressed in many neurons and muscle cells,
and that mutation of these genes and egl-30 affects muscle activity (in
egg laying as well as locomotion) (Mendel et al. 1995; Segalat et al.
1995; Brundage et al. 1996; Korswagen et al. 1997).
In addition, four Ga genes have been identified that were not clear
members of the known mammalian G protein classes (Lochrie et al.
1991; Roayaie et al. 1998). Three of these new Ga genes, gpa-2, gpa-3,
and odr-3, were found to be expressed in a subset of the amphid
neurons, 12 pairs of sensory neurons in the head (Zwaal et al. 1997;
Roayaie et al. 1998). Further analysis of the three new Ga genes indeed
showed that they are involved in several different perception processes:
taste, olfaction, nociception, and dauer formation (Zwaal et al. 1997;
Roayaie et al. 1998).
Although most of the specificity of G protein function lies in the a
subunit, the ~y complex also has significant signaling capabilities. Until
recently only one ~ subunit gene was identified in C. elegans, gpb-l
(van der Voom et al. 1990). Inactivation of this gene leads to embryonic
lethality as a result of inappropriate orientation of the planes of cell
division (Zwaal et al. 1996). We recently found a second ~ subunit gene,
gpb-2, which does not seem to be required for viability (F Simmer, R
Korswagen, G Jansen, K Thijssen, and RHA Plasterk, unpublished
results). Thus far, two y subunit genes have been identified, gpc-l and 2
(G Jansen, K Thijssen, and RHA Plasterk, unpublished results). It
should be noted that the y subunit is small and not well conserved, so
that identification by sequence comparison is not trivial. Therefore, it is
likely that additional y subunit genes remain to be found.
The availability of the genomic sequence and the conservation of all
a subunits during evolution enabled us to identify all Ga genes. Re-