Table 2. Genes showing synthetic interaction with FKS1, FKS2, GAS1, or SMI1 ORF Gene Description of gene product Interaction Cell wall synthesis and regulation (31 genes) YJL095W BCK1 MAPKK-kinase of the cell integrity pathway GAS1, SMI1 YER155C BEM2 GTPase-activating protein for Rho1p FKS1, GAS1, SMI1 YNL233W BNI4 Anchors Chs3p-Chs4p to the bud neck septin ring FKS1, SMI1 YBR023C CHS3 Chitin synthase III FKS1, GAS1, SMI1 YBL061C CHS4 Activator of Chs3p FKS1, SMI1 YLR330W CHS5 Involved in transport of Chs3p from the late Golgi to the chitosome FKS1, GAS1, SMI1 YJL099W CHS6 Involved in transport of Chs3p from the late Golgi to the chitosome FKS1, SMI1 YHR142W CHS7 Facilitates exit of Chs3p from the ER FKS1, SMI1 YGL027C CWH41 Glucosidase I, mutant has a reduced level of ß-1,6-glucan GAS1 YOR030W DFG16 Involved in invasive growth, mutant hypersensitive to calcofluor white FKS1, SMI1 YBL101C ECM21 Mutant hypersensitive to calcofluor white SMI1 YLR443W ECM7 Mutant hypersensitive to calcofluor white GAS1 YLR342W FKS1 ß-1,3-Glucan synthase subunit FKS2 YGR032W FKS2 ß-1,3-Glucan synthase subunit FKS1 YLL043W FPS1 Glycerol channel protein FKS1, SMI1 YMR307W GAS1 GPI-anchored surface glycoprotein with ß-1,3-glucanosyltransferase activity SMI1 YCR046C IMG1 Putative mitochondrial ribosomal protein, null mutant K1 toxin resistant GAS1 YNL322C KRE1 Cell wall protein involved in ß-1,6-glucan synthesis GAS1, SMI1 YLR332W MID2 Sensor for the PKC1-SLT2 cell wall integrity pathway FKS1, SMI1 YDR245W MNN10 Subunit of the Mannan polymerase II complex SMI1 YJL183W MNN11 Subunit of the Mannan polymerase II complex FKS1, SMI1 YOR275C RIM20 Transcription factor involved in stress resistance FKS1, SMI1 YPL089C RLM1 Transcription factor mediating cell integrity pathway response FKS1, GAS1, SMI1 YLR371W ROM2 GDP/GTP exchange factor for Rho1p FKS1, GAS1, SMI1 YBR229C ROT2 Glucosidase II, mutant has a reduced level of ß-1,6-glucan GAS1 YOR008C SLG1 Sensor for the PKC1-SLT2 cell integrity pathway GAS1 YHR030C SLT2 MAP-kinase of the cell integrity pathway FKS1, GAS1, SMI1 YGR229C SMI1 Regulator of ß-1,3-glucan synthesis GAS1 YDR293C SSD1 mRNA-binding protein, may regulate expression of cell integrity pathway targets GAS1 YER111C SWI4 Transcription factor mediating the cell integrity pathway response FKS1, GAS1, SMI1 YML115C VAN1 Component of the Mannan polymerase I complex SMI1 Polarity and secretory pathway function (29 genes) YBR200W BEM1 SH3-domain protein maintaining Cdc42p-Cdc24p at the bud tip SMI1 YPL161C BEM4 Bud emergence protein that activates Cdc42p FKS1, GAS1 YNL271C BNI1 Member of the polarisome with Bud6p, Pea2p, and Spa2p. This complex binds activated Cdc42p and its effector Ste20p and acts as an apical scaffold regulating actin filament assembly at the bud tip FKS1, SMI1 YNR051C BRE5 Activator of Ubp3p that regulates COPII coat assembly FKS1, SMI1 YJL188C BUD19 Mutant defective in bud site selection and bipolar budding GAS1, SMI1 YBR131W CCZ1 Protein involved in vesicular transport and vacuolar assembly SMI1 YNL298W CLA4 Cdc42p effector regulating septin assembly at the bud neck SMI1 YPR030W CSR2 Overexpression rescues chs5 spa2 synthetic lethality FKS1 YBL047C EDE1 Cortical actin patch protein with a role in endocytosis FKS1 YKL048C ELM1 Serine/threonine protein kinase regulating septin network organization FKS1, SMI1 YGL200C EMP24 COPII-coated vesicle protein required for sorting of GPI-anchored proteins GAS1 YBR041W FAT1 Very long-chain acyl-CoA synthetase SMI1 YCR034W FEN1 Involved in fatty acids elongation FKS1 YDL223C HBT1 Target of Hub1p ubiquitination, mutant shows morphological defects FKS1 YGR166W KRE11 Subunit of transport protein particle II complex GAS1, SMI1 YJR073C OPI3 Involved in phosphatidylcholine biosynthesis GAS1 YDR137W RGP1 Acts in a complex with Ric1p as a GTP-GDP exchange factor for Ypt6p FKS1, GAS1 YLR039C RIC1 Acts in a complex with Rgp1p as a GTP-GDP exchange factor for Ypt6p GAS1, SMI1 YDR388W RVS167 Affects cortical actin patch distribution, mutant shows defective endocytosis FKS1, SMI1 YDR351W SBE2 Golgi protein involved in targeting Chs3p and Chr2p to the bud neck SMI1 YOR035C SHE4 Involved in cortical actin patch assembly and endocytosis FKS1 YBL007C SLA1 Cortical actin patch assembly control protein, mutation affects endocytosis FKS1, SMI1 YLL021W SPA2 Member of the polarisome with Bni1p, Bud6p, and Pea2. This complex binds activated Cdc42p and its effector Ste20p and acts as an apical scaffold regulating actin filament assembly at the bud tip FKS1, SMI1 YER151C UBP3 Ubiquitin-specific protease, Ubp3p-Bre5p regulates COPII coat assembly FKS1, SMI1 YDR136C VPS61 Class B vacuolar sorting protein GAS1 YLR261C VPS63 Vacuolar protein sorting GAS1 YKR020W VPS67 Involved in maintenance of actin cytoskeleton and apical bud growth FKS1, SMI1 YLR262C YPT6 GTP-binding protein that regulates vesicle fusion during retrograde transport GAS1, SMI1 YLR338W Questionable ORF, overlaps with VRP1, a cortical actin patch component FKS1 Transcriptional regulation and stress response (22 genes) YDL243C AAD4 Putative aryl-alcohol dehydrogenase GAS1 YNL027W CRZ1 Calcineurin responsive zinc-finger transcription factor FKS1 YKR024C DBP7 RNA helicase required for 60S ribosomal subunit assembly FKS1 YBR121C GRS1 Glycyl-tRNA synthetase, also involved in 3'-end formation of mRNA FKS1 YOR358W HAP5 Transcription factor required for activity of the CCAAT-binding complex GAS1 YJR055W HIT1 Required for growth at high temperature FKS1 YLR384C IKI3 RNA polymerase II transcriptional elongation component SMI1 YIL154C IMP2' Transcriptional activator with a role in DNA repair upon oxidative stress FKS1 YKL032C IXR1 Transcription factor mediating oxygen repression FKS1 YJL124C LSM1 Sm-like RNA-binding protein involved in control of mRNA decay FKS1 YDR378C LSM6 U6 snRNA-associated protein of the Sm-like group FKS1 YMR038C LYS7 Copper chaperone essential for the oxidative protective function of Sod1p SMI1 YML017W PSP2 Suppressor of DNA polymerase mutation FKS1 YLR204W QRI5 Transcription profile suggests involvement in stress responses FKS1 YDR156W RPA14 RNA polymerase I subunit A14 SMI1 YLR357W RSC2 Component of the RSC chromatin remodeling complex regulating RNA polymerase II and III transcription GAS1 YKR072C SIS2 Involved in ion homeostasis GAS1 YDR477W SNF1 Protein kinase with roles in glucose derepression and filamentation FKS1 YOL006C TOP1 DNA topoisomerase I FKS1 YNL064C YDJ1 Hsp40 chaperone required for protein entry into the ER FKS1 YJL046W Lipoate-protein ligase A-related, null mutant hypersensitive to oxidative stress FKS1 YMR073C Possible NAD(P)H oxidoreductase involved in stress response FKS1 Ion homeostasis and signal transduction (5 genes) YGR217W CCH1 Calcium channel protein FKS1, SMI1 YKL190W CNB1 Regulatory subunit of the phosphatase calcineurin FKS1, GAS1, SMI1 YJL117W PHO86 ER protein facilitating incorporation of Pho84p into secretory vesicles SMI1 YDL006W PTC1 Protein phosphatase, acts on MAP kinases such as Hog1p FKS1, GAS1, SMI1 YEL031W SPF1 ATP-dependent calcium pump required for normal ER calcium homeostasis SMI1 Ubiquitin-regulated protein degradation (4 genes) YGR133W PEX4 E2 ubiquitin-conjugating enzyme induced in the unfolded protein response FKS1 YGR135W PRE9 20S (catalytic) proteasome subunit Y13 (3) FKS1, SMI1 YHR200W RPN10 19S (regulatory) proteasome subunit, homolog of the mammalian S5a protein FKS1, SMI1 YBR082C UBC4 E2 ubiquitin-conjugating enzyme FKS1, SMI1 Cell cycle (3 genes) YGL240W DOC1 Component of the anaphase-promoting complex FKS1, SMI1 YPL031C PHO85 Cyclin-dependent protein kinase that interacts with cyclin Pho80p FKS1, GAS1, SMI1 YNL171C Overlaps with APC1, an essential subunit of the anaphase-promoting complex FKS1, SMI1 Other (17 genes) YHR129C ARP1 Centractin SMI1 YMR116C ASC1 40S ribosomal protein that affects cell size SMI1 YPR135W CTF4 DNA-directed DNA polymerase -binding protein SMI1 YHR191C CTF8 Putative kinetochore protein SMI1 YDR440W DOT1 Involved in telomere silencing and in the meiotic arrest checkpoint GAS1 YDR508C GNP1 High-affinity glutamine permease FKS1, GAS1 YDR162C NBP2 Nap1p-binding protein GAS1, SMI1 YHR004C NEM1 Protein required for nuclear morphology GAS1 YJL208C NUC1 Nuclease, mitochondrial FKS1 YER178W PDA1 Pyruvate dehydrogenase complex E1--subunit SMI1 YMR205C PFK2 ß-subunit of the 6-phosphofructokinase SMI1 YNL069C RPL16B Ribosomal protein L16, nearly identical to Rpl16Ap FKS1 YOR312C RPL20B Ribosomal protein L20, nearly identical to Rpl20Ap FKS1 YFR032C-A RPL29 Ribosomal protein L29 SMI1 YGR214W RPS0A 40S ribosomal protein SMI1 YJL136C RPS21B Ribosomal protein S21B FKS1 YBR166C TYR1 Prephenate dehydrogenase in the tyrosine biosynthesis pathway SMI1 Unknown (24 genes) YMR318C ADH6 NADPH-dependent cinnamyl-alcohol dehydrogenase GAS1 YJR118C ILM1 Null mutant shows increased loss of mitochondrial DNA FKS1, SMI1 YLR320W MMS22 Unknown FKS1, SMI1 YNL294C RIM21 Protein of unknown function FKS1, GAS1 YAL053W Expression is upregulated in an fks1 mutant GAS1 YBL062W Questionable ORF, overlaps with CHS4 FKS1 YGL046W Hypothetical protein, merged with RIM8/YGL045W FKS1, SMI1 YGL081W Phosphopeptide-binding protein with a forkhead-associated (FHA) domain FKS1 YGL110C Member of the CUE domain family, which binds ubiquitin-conjugating enzymes FKS1, GAS1 YGL196W Hypothetical protein FKS1 YGR237C Weak similarity to YOR019W SMI1 YIL121W Member of the multidrug-resistance 12-spanner family GAS1 YLR021W Hypothetical protein FKS1 YLR358C Unknown SMI1 YML117W Unknown GAS1, SMI1 YMR313C Unknown GAS1 YMR316C-A Protein of unknown function GAS1 YMR317W Unknown GAS1 YMR326C Protein with high similarity to Ynr077p GAS1 YOL003C Similar to Erf2p, Ydr459p, and others in a cysteine-rich domain FKS1, SMI1 YPL041C Hypothetical protein FKS1, GAS1 YPL077C Weak similarity to YBR197C SMI1 YPL144W Unknown FKS1 YPL261C Putative GPI-anchored protein that may be involved in cell wall maintenance FKS1 ORF, open reading frame; ER, endoplasmic reticulum.