TABLE 2.
Comparison between the functions of proteins involved in the pheromone response pathway and MAPK cascades in heterothallic and homothallic species
| Protein |
Neurospora crassa (heterothallic) |
Sordaria macrospora (homothallic) |
||||
|---|---|---|---|---|---|---|
| Gene | Mutant phenotypesa | Gene | Mutant phenotypesb | |||
| α-Factor pheromone | ccg4 | Male sterility* in MAT1-1 partner (106) | ppg1 | No sexual defects (128) | Δppg1/Δppg2: reduced ascomatal production (128) | Δppg1/Δpre1: greatly reduced ascomatal production (128) |
| a-Factor pheromone | mfa-1 | Male sterility in MAT1-2 partner (106); aberrant female development (108) | ppg2 | No sexual defects (128) | Δppg2/Δpre2: greatly reduced ascomatal production (128) | |
| α-Factor receptor | pre2 | No protoascomatal maturation in MAT1-2 partner (24) | pre2 | No sexual defects (128) | Δpre1/Δpre2: no protoascomatal maturation (128) | Δppg2/Δpre2: greatly reduced ascomatal production (128) |
| a-Factor receptor | pre1 | No protoascomatal maturation in MAT1-1 partner (107) | pre1 | No sexual defects (128) | Δppg1/Δpre1: greatly reduced ascomatal production (128) | |
| Gα subunit | gna1 | Unusually shaped protoascomata that do not grow towards spermatia (150) | gsa1 | Delayed and reduced ascomatal production (152) | Δgsa1/Δgsa2 and Δgsa1/Δgsa3: greatly reduced protoascomatal production and no protoascomatal maturation (152) | |
| gna2 | No sexual defects (151) | gsa2 | No sexual defects (152) | |||
| gsa3 | Greatly reduced ascospore germination (152) | |||||
| Gβ subunit | gnb1 | No protoascomatal maturation (111, 153) | ||||
| Gγ subunit | gng1 | No protoascomatal maturation† (153) | ||||
| MAPKKK | nrc1 | No protoascomatal production‡ (212) | mik2 | No protoascomatal maturation (160) | ||
| MAPKK | mek2 | No protoascomatal maturation (160) | ||||
| MAPK | mak2 | No protoascomatal production (155) | mak2 | No protoascomatal maturation (160) | ||
| Transcriptional regulator | pp-1 | No protoascomatal production (155) | ste12 | Reduced asci production, fragile walls of asci and ascospores (193) | ||
| MAPKKK | mik1 | No protoascomatal production (110) | mik1 | No protoascomatal maturation (159) | ||
| MAPKK | mek1 | No protoascomatal production (110) | mek1 | No protoascomatal maturation (159) | ||
| MAPK | mak1 | No protoascomatal production (110) | mak1 | No protoascomatal maturation (159) | ||
| Rrg-1 | No protoascomatal production (156) | |||||
| MAPKKK | os-4 | No protoascomatal production (157) | ||||
| MAPKK | os-5 | No protoascomatal production (157) | ||||
| MAPK | os-2 | No protoascomatal production (156) | ||||
| Adenylyl cyclase | cr-1 | Delayed ascomatal development (213) | sac1 | Reduced ascomatal size and ascospore germination (152) | ||
a
*, Male sterility indicates that an isolate is unable to act as the male partners; †, no protoascomatal maturation indicates that protoascomata are produced but do not mature into ascomata; ‡, no protoascomatal production indicates that protoascomata are not formed at all.
b
Wild-type (proto)ascomatal production > reduced (proto)ascomatal production > greatly reduced (proto)ascomatal production.