MATA1 Summary Help

Standard Name MATA1 1
Alias A1
Feature Type not in systematic sequence of S288C
Description Expressed copy (at MATa) of a1; homeobox-domain protein that, along with alpha2, represses transcription of haploid-specific genes in diploid cells; MATa1 pre-mRNA splicing requires Bud13p and Ist3p; a1 sequence is not present in SGD because the sequenced S288C strain is MATalpha, not MATa (2, 3, 4, 5, 6 and see Summary Paragraph)
Gene Ontology Annotations All MATA1 GO evidence and references
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Classical genetics
External Links All Associated Seq | Search all NCBI (Entrez)
Primary SGDIDS000029660

a1 is one of two genes encoded by the a mating type cassette in S. cerevisiae (4). The mating type of S. cerevisiae is determined by the genetic composition of the MAT locus (7, 4, 5). Haploids of the a mating type express the genes a1 and a2 from the MAT locus while haploids of the alpha mating type express alpha1 and alpha2 from MAT (7, 4, 5). Some of the cells within a given colony are capable of switching mating type by changing the genetic composition of the MAT locus (8); more information on mating type switching can be found in the summary paragraph for MAT and references cited therein. Diploid cells are normally heterozygous (a/alpha) at the MAT locus (7, 4, 5).

a1 encodes a homeodomain protein involved in transcriptional regulation of mating-type-specific genes (2, 3, 4, 5). The a1 protein is produced in haploid MATa cells, but does not play any known role in a-specific gene expression, and is rapidly degraded (4, 9). In a/alpha diploid cells, a1p interacts with another homeodomain protein, alpha2p, to bind DNA as a heterodimer to repress transcription of haploid-specific genes (2, 4, 3, 5, 10, 11, 12). The interaction between a1p and alpha2p stabilizes both proteins, and alters their DNA binding specificities (2, 10, 9, 13).

Note: The maps and sequences within SGD reflect the fact that a MATalpha strain was used in the systematic sequencing project. Accordingly, there are two copies of the alpha1 and alpha2 genes; one pair (MATalpha1/YCR040W and MATalpha2/YCR039C) corresponds to the MAT locus, and the other (HMLalpha1/YCL066W and HMLalpha2/YCL067C) to the HML locus. There are ORFs assigned to the copies of a1 and a2 found at HMR (HMRa1/YCR097W) and (HMRa2/YCR096C); locus entries are included for MATa1 and MATa2 but they do not have ORFs associated with them. There are GenBank sequences available from all of the locus pages describing a1, a2, alpha1, and alpha2; the Genbank accession for the MATa cassette is V01313.

Last updated: 2000-08-15 Contact SGD

References cited on this page View Complete Literature Guide for MATA1
1) Nasmyth KA, et al.  (1981) A position effect in the control of transcription at yeast mating type loci. Nature 289(5795):244-50
2) Goutte C and Johnson AD  (1988) a1 protein alters the DNA binding specificity of alpha 2 repressor. Cell 52(6):875-82
3) Dranginis AM  (1990) Binding of yeast a1 and alpha 2 as a heterodimer to the operator DNA of a haploid-specific gene. Nature 347(6294):682-5
4) Herskowitz I  (1989) A regulatory hierarchy for cell specialization in yeast. Nature 342(6251):749-57
5) Herskowitz I, et al.  (1992) "Mating-type determination and mating-type interconversion in Saccharomyces cerevisiae." Pp. 583-656 in The Molecular and Cellular Biology of the Yeast Saccharomyces: Gene Expression, edited by Jones EW, Pringle JR and Broach JR. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press
6) Tuo S, et al.  (2012) Apparent defect in yeast bud-site selection due to a specific failure to splice the pre-mRNA of a regulator of cell-type-specific transcription. PLoS One 7(10):e47621
7) Herskowitz I  (1983) Cellular differentiation, cell lineages, and transposable genetic cassettes in yeast. Curr Top Dev Biol 18:1-14
8) Haber JE  (1998) Mating-type gene switching in Saccharomyces cerevisiae. Annu Rev Genet 32:561-99
9) Johnson PR, et al.  (1998) Degradation signal masking by heterodimerization of MATalpha2 and MATa1 blocks their mutual destruction by the ubiquitin-proteasome pathway. Cell 94(2):217-27
10) Goutte C and Johnson AD  (1993) Yeast a1 and alpha 2 homeodomain proteins form a DNA-binding activity with properties distinct from those of either protein. J Mol Biol 233(3):359-71
11) Goutte C and Johnson AD  (1994) Recognition of a DNA operator by a dimer composed of two different homeodomain proteins. EMBO J 13(6):1434-42
12) Li T, et al.  (1998) Crystal structure of the MATa1/MATalpha2 homeodomain heterodimer in complex with DNA containing an A-tract. Nucleic Acids Res 26(24):5707-18
13) Stark MR, et al.  (1999) A trans-acting peptide activates the yeast a1 repressor by raising its DNA-binding affinity. EMBO J 18(6):1621-9