scholarly journals Pheromones and pheromone receptors are the primary determinants of mating specificity in the yeast Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 463-476 ◽  
Author(s):  
A Bender ◽  
G F Sprague
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Types ◽  
Haploid Cell ◽  
Wild Type ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
A Cells ◽  
Alpha Factor ◽  
A Cell ◽  
Specific Proteins

Abstract Saccharomyces cerevisiae has two haploid cell types, a and alpha, each of which produces a unique set of proteins that participate in the mating process. We sought to determine the minimum set of proteins that must be expressed to allow mating and to confer specificity. We show that the capacity to synthesize alpha-factor pheromone and a-factor receptor is sufficient to allow mating by mat alpha 1 mutants, mutants that normally do not express any alpha- or a-specific products. Likewise, the capacity to synthesize a-factor receptor and alpha-factor pheromone is sufficient to allow a ste2 ste6 mutants, which do not produce the normal a cell pheromone and receptor, to mate with wild-type a cells. Thus, the a-factor receptor and alpha-factor pheromone constitute the minimum set of alpha-specific proteins that must be produced to allow mating as an alpha cell. Further evidence that the pheromones and pheromone receptors are important determinants of mating specificity comes from studies with mat alpha 2 mutants, cells that simultaneously express both pheromones and both receptors. We created a series of strains that express different combinations of pheromones and receptors in a mat alpha 2 background. These constructions reveal that mat alpha 2 mutants can be made to mate as either a cells or as alpha cells by causing them to express only the pheromone and receptor set appropriate for a particular cell type. Moreover, these studies show that the inability of mat alpha 2 mutants to respond to either pheromone is a consequence of two phenomena: adaptation to an autocrine response to the pheromones they secrete and interference with response to alpha factor by the a-factor receptor.

scholarly journals Mutants of Saccharomyces cerevisiae unresponsive to cell division control by polypeptide mating hormone.

1980 ◽  
Vol 85 (3) ◽  
pp. 811-822 ◽  
Author(s):  
L H Hartwell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Types ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Alpha Cells ◽  
Wild Type ◽  
Cell Type ◽  
Mating Test ◽  
Alpha Factor ◽  
Cell Division Control

Temperature-sensitive mutations that produce insensitivity to division arrest by alpha-factor, a mating pheromone, were isolated in an MATa strain of Saccharomyces cerevisiae and shown by complementation studies to difine eight genes. All of these mutations (designated ste) produce sterility at the restrictive temperature in MATa cells, and mutations in seven of the genes produce sterility in MAT alpha cells. In no case was the sterility associated with these mutations coorectible by including wild-type cells of the same mating type in the mating test nor did nay of the mutants inhibit mating of the wild-type cells; the defect appears to be intrinsic to the cell for mutations in each of the genes. Apparently, none of the mutants is defective exclusively in division arrest by alpha-factor, as the sterility of none is suppressed by a temperature-sensitive cdc 28 mutation (the latter imposes division arrest at the correct cell cycle stage for mating). The mutants were examined for features that are inducible in MATa cells by alpha-factor (agglutinin synthesis as well as division arrest) and for the characteristics that constitutively distinguish MATa from MAT alpha cells (a-factor production, alpha-factor destruction). ste2 Mutants are defective specifically in the two inducible properties, whereas ste4, 5, 7, 8, 9, 11, and 12 mutants are defective, to varying degrees, in constitutive as well as inducible aspects. Mutations in ste8 and 9 assume a polar budding pattern unlike either MATa or MAT alpha cells but characteristic of MATa/alpha cells. This study defines seven genes that function in two cell types (MATa and alpha) to control the differentiation of cell type and one gene, ste2, that functions exclusively in MATa cells to mediate responsiveness to polypeptide hormone.

scholarly journals Suppressors of a gpa1 mutation cause sterility in Saccharomyces cerevisiae.

Genetics ◽  
1988 ◽  
Vol 119 (4) ◽  
pp. 797-804
Author(s):  
I Miyajima ◽  
N Nakayama ◽  
M Nakafuku ◽  
Y Kaziro ◽  
K Arai ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fusion Gene ◽  
Lacz Fusion ◽  
Wild Type ◽  
Cell Type ◽  
Recessive Mutations ◽  
Cycle Arrest ◽  
Alpha Factor ◽  
A Cell ◽  
Mating Factor

Abstract The Saccharomyces cerevisiae GPA1 gene encodes a protein highly homologous to the alpha subunit of mammalian G proteins and is essential for haploid cell growth. We have selected 77 mutants able to suppress the lethality resulting from disruption of GPA1 (gpa1::HIS3). Two strains bearing either of two recessive mutations, sgp1 and sgp2, in combination with the disruption mutation, showed a cell type nonspecific sterile phenotype, yet expressed the major alpha-factor gene (MF alpha 1) as judged by the ability to express a MF alpha 1-lacZ fusion gene. The sgp1 mutation was closely linked to gpa1::HIS3 and probably occurred at the GPA1 locus. The sgp2 mutation was not linked to GPA1 and was different from the previously identified cell type nonspecific sterile mutations (ste4, ste5, ste7, ste11 and ste12). sgp2 GPA1 cells showed a fertile phenotype, indicating that the mating defect caused by sgp2 is associated with the loss of GPA1 function. While expression of a FUS1-lacZ fusion gene was induced in wild-type cells by the addition of alpha-factor, mutants bearing sgp1 or sgp2 as well as gpa1::HIS3 constitutively expressed FUS1-lacZ. These observations suggest that GPA1 (SGP1) and SGP2 are involved in mating factor-mediated signal transduction, which causes both cell cycle arrest in the late G1 phase and induction of genes necessary for mating such as FUS1.

scholarly journals The Anaphase-promoting Complex Promotes Actomyosin-Ring Disassembly during Cytokinesis in Yeast

2009 ◽  
Vol 20 (4) ◽  
pp. 1201-1212 ◽  
Author(s):  
Gregory H. Tully ◽  
Ryuichi Nishihama ◽  
John R. Pringle ◽  
David O. Morgan
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ubiquitin Ligase ◽  
Myosin Light Chain ◽  
Anaphase Promoting Complex ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Division Site ◽  
Specific Proteins ◽  
Mutant Cells ◽  
In Cells

The anaphase-promoting complex (APC) is a ubiquitin ligase that controls progression through mitosis by targeting specific proteins for degradation. It is unclear whether the APC also contributes to the control of cytokinesis, the process that divides the cell after mitosis. We addressed this question in the yeast Saccharomyces cerevisiae by studying the effects of APC mutations on the actomyosin ring, a structure containing actin, myosin, and several other proteins that forms at the division site and is important for cytokinesis. In wild-type cells, actomyosin-ring constituents are removed progressively from the ring during contraction and disassembled completely thereafter. In cells lacking the APC activator Cdh1, the actomyosin ring contracts at a normal rate, but ring constituents are not disassembled normally during or after contraction. After cytokinesis in mutant cells, aggregates of ring proteins remain at the division site and at additional foci in other parts of the cell. A key target of APCCdh1 is the ring component Iqg1, the destruction of which contributes to actomyosin-ring disassembly. Deletion of CDH1 also exacerbates actomyosin-ring disassembly defects in cells with mutations in the myosin light-chain Mlc2, suggesting that Mlc2 and the APC employ independent mechanisms to promote ring disassembly during cytokinesis.

scholarly journals Molecular cloning and characterization of the STE7 and STE11 genes of Saccharomyces cerevisiae.

1985 ◽  
Vol 5 (8) ◽  
pp. 1878-1886 ◽  
Author(s):  
D T Chaleff ◽  
K Tatchell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Cloning ◽  
Mating Type ◽  
Cell Types ◽  
Transcriptional Level ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Genetic Techniques ◽  
Conjugation Process ◽  
Mat Locus

In the yeast Saccharomyces cerevisiae, haploid cells occur in one of the two cell types, a or alpha. The allele present at the mating type (MAT) locus plays a prominent role in the control of cell type expression. An important consequence of the elaboration of cell type is the ability of cells of one mating type to conjugate with cells of the opposite mating type, resulting in yet a third cell type, an a/alpha diploid. Numerous genes that are involved in the expression of cell type and the conjugation process have been identified by standard genetic techniques. Molecular analysis has shown that expression of several of these genes is subject to control on the transcriptional level by the MAT locus. Two genes, STE7 and STE11, are required for mating in both haploid cell types; ste7 and ste11 mutants are sterile. We report here the molecular cloning of STE7 and STE11 genes and show that expression of these genes is not regulated transcriptionally by the MAT locus. We also have genetically mapped the STE11 gene to chromosome XII, 40 centimorgans from ura4.

scholarly journals The a-factor pheromone of Saccharomyces cerevisiae is essential for mating.

1988 ◽  
Vol 8 (3) ◽  
pp. 1309-1318 ◽  
Author(s):  
S Michaelis ◽  
I Herskowitz
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Double Mutant ◽  
Protein Transport ◽  
Factor Activity ◽  
Structural Genes ◽  
Wild Type ◽  
Mating Partner ◽  
Cycle Arrest ◽  
A Cells ◽  
A Cell

The Saccharomyces cerevisiae pheromone a-factor is produced by a cells and interacts with alpha cells to cause cell cycle arrest and other physiological responses associated with mating. Two a-factor structural genes, MFA1 and MFA2, have been previously cloned with synthetic probes based on the a-factor amino acid sequence (A. Brake, C. Brenner, R. Najarian, P. Laybourn, and J. Merryweather, cited in M.-J. Gething [ed.], Protein transport and secretion, 1985). We have examined the function of these genes in a-factor production and mating by construction and analysis of chromosomal null mutations. mfa1 and mfa2 single mutants each exhibited approximately half the wild-type level of a-factor activity and were proficient in mating, whereas the mfa1 mfa2 double mutant produced no a-factor and was unable to mate. These results demonstrate that both genes are functional, that each gene makes an equivalent contribution to the a-factor activity and mating capacity of a cells, and that a-factor plays an essential role in mating. Strikingly, exogenous a-factor did not alleviate the mating defect of the double mutant, suggesting that an a cell must be producing a-factor to be an effective mating partner.

The a-factor pheromone of Saccharomyces cerevisiae is essential for mating

1988 ◽  
Vol 8 (3) ◽  
pp. 1309-1318 ◽  
Author(s):  
S Michaelis ◽  
I Herskowitz
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Double Mutant ◽  
Protein Transport ◽  
Factor Activity ◽  
Structural Genes ◽  
Wild Type ◽  
Mating Partner ◽  
Cycle Arrest ◽  
A Cells ◽  
A Cell

The Saccharomyces cerevisiae pheromone a-factor is produced by a cells and interacts with alpha cells to cause cell cycle arrest and other physiological responses associated with mating. Two a-factor structural genes, MFA1 and MFA2, have been previously cloned with synthetic probes based on the a-factor amino acid sequence (A. Brake, C. Brenner, R. Najarian, P. Laybourn, and J. Merryweather, cited in M.-J. Gething [ed.], Protein transport and secretion, 1985). We have examined the function of these genes in a-factor production and mating by construction and analysis of chromosomal null mutations. mfa1 and mfa2 single mutants each exhibited approximately half the wild-type level of a-factor activity and were proficient in mating, whereas the mfa1 mfa2 double mutant produced no a-factor and was unable to mate. These results demonstrate that both genes are functional, that each gene makes an equivalent contribution to the a-factor activity and mating capacity of a cells, and that a-factor plays an essential role in mating. Strikingly, exogenous a-factor did not alleviate the mating defect of the double mutant, suggesting that an a cell must be producing a-factor to be an effective mating partner.

scholarly journals IME4, a gene that mediates MAT and nutritional control of meiosis in Saccharomyces cerevisiae.

1992 ◽  
Vol 12 (3) ◽  
pp. 1078-1086 ◽  
Author(s):  
J C Shah ◽  
M J Clancy
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nutrient Availability ◽  
Cell Types ◽  
Cell Type ◽  
Transcript Accumulation ◽  
Yeast Saccharomyces Cerevisiae ◽  
New Gene ◽  
Low Levels ◽  
Diploid Cells

In the yeast Saccharomyces cerevisiae, sporulation occurs in response to nutritional and genetic signals. The process is initiated when nutrient availability limits mitotic growth, but only in MATa/MAT alpha diploid cells. Under these conditions, the cells express an activator of meiosis (IME1), which is required for the expression of early sporulation-specific genes. We describe a new gene, IME4, whose activity is essential for IME1 transcript accumulation and sporulation. The IME4 transcript was induced in starved MATa/MAT alpha diploids but not in other cell types. In addition, excess IME4 promoted sporulation in mat-insufficient cells. Thus, IME4 appears to activate IME1 in response to cell type and nutritional signals. We have also explored the interactions between IME4 and two genes that are known to regulate IME1 expression. Normally, cells that lack complete MAT information cannot sporulate; when such strains lack RME1 activity or contain the semidominant RES1-1 mutation, however, they can express IME1 and sporulate to low levels. Our results show that mat-insufficient strains containing rme1::LEU2 or RES1-1 bypass mutations still retain MAT control of IME4 expression. Even though IME4 levels remained low, the rme1::LEU2 and RES1-1 mutations allowed IME1 accumulation, implying that these mutations do not require IME4 to exert their effects. In accord with this interpretation, the RES1-1 mutation allowed IME1 accumulation in MATa/MAT alpha strains that contain ime4::LEU2 alleles. These strains still sporulated poorly, suggesting that IME4 plays a role in sporulation in addition to promoting IME1 transcript accumulation. IME4 is located between ADE5 and LYS5 on chromosome VII.

Molecular cloning and characterization of the STE7 and STE11 genes of Saccharomyces cerevisiae

1985 ◽  
Vol 5 (8) ◽  
pp. 1878-1886
Author(s):  
D T Chaleff ◽  
K Tatchell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Cloning ◽  
Mating Type ◽  
Cell Types ◽  
Transcriptional Level ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Genetic Techniques ◽  
Conjugation Process ◽  
Mat Locus

In the yeast Saccharomyces cerevisiae, haploid cells occur in one of the two cell types, a or alpha. The allele present at the mating type (MAT) locus plays a prominent role in the control of cell type expression. An important consequence of the elaboration of cell type is the ability of cells of one mating type to conjugate with cells of the opposite mating type, resulting in yet a third cell type, an a/alpha diploid. Numerous genes that are involved in the expression of cell type and the conjugation process have been identified by standard genetic techniques. Molecular analysis has shown that expression of several of these genes is subject to control on the transcriptional level by the MAT locus. Two genes, STE7 and STE11, are required for mating in both haploid cell types; ste7 and ste11 mutants are sterile. We report here the molecular cloning of STE7 and STE11 genes and show that expression of these genes is not regulated transcriptionally by the MAT locus. We also have genetically mapped the STE11 gene to chromosome XII, 40 centimorgans from ura4.

IME4, a gene that mediates MAT and nutritional control of meiosis in Saccharomyces cerevisiae

1992 ◽  
Vol 12 (3) ◽  
pp. 1078-1086
Author(s):  
J C Shah ◽  
M J Clancy
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nutrient Availability ◽  
Cell Types ◽  
Cell Type ◽  
Transcript Accumulation ◽  
Yeast Saccharomyces Cerevisiae ◽  
New Gene ◽  
Low Levels ◽  
Diploid Cells

In the yeast Saccharomyces cerevisiae, sporulation occurs in response to nutritional and genetic signals. The process is initiated when nutrient availability limits mitotic growth, but only in MATa/MAT alpha diploid cells. Under these conditions, the cells express an activator of meiosis (IME1), which is required for the expression of early sporulation-specific genes. We describe a new gene, IME4, whose activity is essential for IME1 transcript accumulation and sporulation. The IME4 transcript was induced in starved MATa/MAT alpha diploids but not in other cell types. In addition, excess IME4 promoted sporulation in mat-insufficient cells. Thus, IME4 appears to activate IME1 in response to cell type and nutritional signals. We have also explored the interactions between IME4 and two genes that are known to regulate IME1 expression. Normally, cells that lack complete MAT information cannot sporulate; when such strains lack RME1 activity or contain the semidominant RES1-1 mutation, however, they can express IME1 and sporulate to low levels. Our results show that mat-insufficient strains containing rme1::LEU2 or RES1-1 bypass mutations still retain MAT control of IME4 expression. Even though IME4 levels remained low, the rme1::LEU2 and RES1-1 mutations allowed IME1 accumulation, implying that these mutations do not require IME4 to exert their effects. In accord with this interpretation, the RES1-1 mutation allowed IME1 accumulation in MATa/MAT alpha strains that contain ime4::LEU2 alleles. These strains still sporulated poorly, suggesting that IME4 plays a role in sporulation in addition to promoting IME1 transcript accumulation. IME4 is located between ADE5 and LYS5 on chromosome VII.

Dendritic cells of the human epidermis: immuno-electron microscopic studies of la antigen reactivity

1978 ◽  
Vol 36 (2) ◽  
pp. 644-645
Author(s):  
G. Rowden ◽  
M. G. Lewis ◽  
T. M. Phillips
Keyword(s):  
Dendritic Cells ◽  
Langerhans Cells ◽  
Cell Types ◽  
Cell Type ◽  
Electron Microscopic ◽  
La Antigen ◽  
Microscopic Studies ◽  
A Cell ◽  
C3 Receptors ◽  
Antigen Reactivity

Langerhans cells of mammalian stratified squamous epithelial have proven to be an enigma since their discovery in 1868. These dendritic suprabasal cells have been considered as related to melanocytes either as effete cells, or as post divisional products. Although grafting experiments seemed to demonstrate the independence of the cell types, much confusion still exists. The presence in the epidermis of a cell type with morphological features seemingly shared by melanocytes and Langerhans cells has been especially troublesome. This so called "indeterminate", or " -dendritic cell" lacks both Langerhans cells granules and melanosomes, yet it is clearly not a keratinocyte. Suggestions have been made that it is related to either Langerhans cells or melanocyte. Recent studies have unequivocally demonstrated that Langerhans cells are independent cells with immune function. They display Fc and C3 receptors on their surface as well as la (immune region associated) antigens.

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