scholarly journals Interaction with Tap42 Is Required for the Essential Function of Sit4 and Type 2A Phosphatases

2003 ◽  
Vol 14 (11) ◽  
pp. 4342-4351 ◽  
Author(s):  
Huamin Wang ◽  
Xiaodong Wang ◽  
Yu Jiang

In Saccharomyces cerevisiae, Pph21 and Pph22 are the two catalytic subunits of type 2A phosphatase (PP2Ac), and Sit4 is a major form of 2A-like phosphatase. The function of these phosphatases requires their association with different regulatory subunits. In addition to the conventional regulatory subunits, namely, the A and B subunits for Pph21/22 and the Sap proteins for Sit4, these phosphatases have been found to associate with a protein termed Tap42. In this study, we demonstrated that Sit4 and PP2Ac interact with Tap42 via an N-terminal domain that is conserved in all type 2A and 2A-like phosphatases. We found that the Sit4 phosphatase in the sit4-102 strain contains a reverse-of-charge amino acid substitution within its Tap42 binding domain and is defective for formation of the Tap42-Sit4 complex. Our results suggest that the interaction with Tap42 is required for the activity as well as for the essential function of Sit4 and PP2Ac. In addition, we showed that Tap42 is able to interact with two other 2A-like phosphatases, Pph3 and Ppg1.

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 447-452 ◽  
Author(s):  
Jeffrey S Thompson ◽  
Marilyn L Snow ◽  
Summer Giles ◽  
Leslie E McPherson ◽  
Michael Grunstein

Abstract Fourteen novel single-amino-acid substitution mutations in histone H3 that disrupt telomeric silencing in Saccharomyces cerevisiae were identified, 10 of which are clustered within the α1 helix and L1 loop of the essential histone fold. Several of these mutations cause derepression of silent mating locus HML, and an additional subset cause partial loss of basal repression at the GAL1 promoter. Our results identify a new domain within the essential core of histone H3 that is required for heterochromatin-mediated silencing.


1993 ◽  
Vol 13 (4) ◽  
pp. 2554-2563 ◽  
Author(s):  
D Wojciechowicz ◽  
C F Lu ◽  
J Kurjan ◽  
P N Lipke

alpha-Agglutinin is a cell adhesion glycoprotein expressed on the cell wall of Saccharomyces cerevisiae alpha cells. Binding of alpha-agglutinin to its ligand a-agglutinin, expressed by a cells, mediates cell-cell contact during mating. Analysis of truncations of the 650-amino-acid alpha-agglutinin structural gene AG alpha 1 delineated functional domains of alpha-agglutinin. Removal of the C-terminal hydrophobic sequence allowed efficient secretion of the protein and loss of cell surface attachment. This cell surface anchorage domain was necessary for linkage to a glycosyl phosphatidylinositol anchor. A construct expressing the N-terminal 350 amino acid residues retained full a-agglutinin-binding activity, localizing the binding domain to the N-terminal portion of alpha-agglutinin. A 278-residue N-terminal peptide was inactive; therefore, the binding domain includes residues between 278 and 350. The segment of alpha-agglutinin between amino acid residues 217 and 308 showed significant structural and sequence similarity to a consensus sequence for immunoglobulin superfamily variable-type domains. The similarity of the alpha-agglutinin-binding domain to mammalian cell adhesion proteins suggests that this structure is a highly conserved feature of adhesion proteins in diverse eukaryotes.


1994 ◽  
Vol 130 (6) ◽  
pp. 569-574 ◽  
Author(s):  
Kyosuke Imasaki ◽  
Tomonobu Hasegawa ◽  
Taijiro Okabe ◽  
Yoshiyuki Sakai ◽  
Masafumi Haji ◽  
...  

Imasaki K, Hasegawa T. Okabe T. Sakai Y. Haji M. Takayanagi R, Nawata H. Single amino acid substitution (840Arg → His) in the hormone-binding domain of the androgen receptor leads to incomplete androgen insensitivity syndrome associated with a thermolabile androgen receptor. Eur I Endocrinol 1994;130:569–74. ISSN 0804–4643 We have characterized the androgen receptor in a Japanese girl and her maternal cousin in a family with incomplete androgen insensitivity syndrome, and have investigated the molecular basis. Wholecell androgen binding assay in cultured genital skin fibroblasts from both patients showed a normal maximum binding capacity and a normal apparent dissociation constant. However, androgen binding in fibroblasts from both patients decreased to 30% when the assay temperature was raised from 30°C to 41°C, indicating the presence of the thermolability of ligand binding to the androgen receptor. Sequence analysis of the coding exons of the androgen receptor gene from the patients revealed a single nucleotide substitution at position 2881 in exon G, resulting in the conversion of arginine (CGT) to histidine (CAT) at amino acid position 840 in the hormone-binding domain of the androgen receptor. The family study showed that the mothers and the maternal grandmother of the patients are heterozygous carriers for this mutation, whereas the father does not carry it, supporting the view that androgen insensitivity syndrome is an X chromosome-linked disorder. The single amino acid substitution may explain the qualitative abnormality of the androgen receptor displaying thermolability, which is thought to be the pathogenesis of incomplete androgen insensitivity syndrome in the patients. Kyosuke Imasaki, Third Department of Internal Medicine, Faculty of Medicine, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812, Japan


Blood ◽  
1998 ◽  
Vol 92 (9) ◽  
pp. 3260-3267 ◽  
Author(s):  
Ronggang Wang ◽  
Peter J. Newman

Platelet membrane glycoprotein IIIa (GPIIIa) is the most polymorphic integrin subunit in man, with at least seven recognized allelic isoforms present in the human gene pool. Whether these allelic variants of the GPIIb-IIIa complex differ in the ability to interact with the adhesive ligand fibrinogen (Fg) is still unknown. Since the Pena and Penb allelic forms of GPIIIa are distinguished by a single Arg143Gln amino acid substitution within the RGD binding domain of GPIIIa and anti-Pena human alloantibodies have been shown to bind GPIIb-IIIa on the platelet surface and inhibit ADP-induced platelet aggregation, we expressed both forms of this integrin in Chinese hamster ovary (CHO) cells and examined the relative adhesive properties. Both allelic forms of GPIIb-IIIa were expressed on the cell surface and were recognized by a well-characterized panel of murine and human monoclonal and polyclonal antibodies. Like Pena, the Penb form of GPIIb-IIIa could undergo conformational changes in response to RGD peptide binding, and could be induced by activating antibodies to bind Fg and the Fg mimetic antibody P1-55. The binding affinity for Fg of the Pena form of the GPIIb-IIIa complex was not significantly different from that of the Penb form, nor was its ability to signal to focal adhesion kinase, suggesting that Arg143Gln polymorphism has little or no effect on integrin function. Examination of the functional consequences of other integrin polymorphisms may be necessary to determine whether they constitute a risk factor for thrombosis or hemorrhage. © 1998 by The American Society of Hematology.


1991 ◽  
Vol 11 (2) ◽  
pp. 754-764 ◽  
Author(s):  
R Yano ◽  
M Nomura

The SRP3-1 mutation is an allele-specific suppressor of temperature-sensitive mutations in the largest subunit (A190) of RNA polymerase I from Saccharomyces cerevisiae. Two mutations known to be suppressed by SRP3-1 are in the putative zinc-binding domain of A190. We have cloned the SRP3 gene by using its suppressor activity and determined its complete nucleotide sequence. We conclude from the following evidence that the SRP3 gene encodes the second-largest subunit (A135) of RNA polymerase I. First, the deduced amino acid sequence of the gene product contains several regions with high homology to the corresponding regions of the second-largest subunits of RNA polymerases of various origins, including those of RNA polymerase II and III from S. cerevisiae. Second, the deduced amino acid sequence contains known amino acid sequences of two tryptic peptides from the A135 subunit of RNA polymerase I purified from S. cerevisiae. Finally, a strain was constructed in which transcription of the SRP3 gene was controlled by the inducible GAL7 promoter. When this strain, which can grow on galactose but not on glucose, was shifted from galactose medium to glucose medium, a large decrease in the cellular concentration of A135 was observed by Western blot analysis. We have also identified the specific amino acid alteration responsible for suppression by SRP3-1 and found that it is located within the putative zinc-binding domain conserved among the second-largest subunits of eucaryotic RNA polymerases. From these results, it is suggested that this putative zinc-binding domain is in physical proximity to and interacts with the putative zinc-binding domain of the A190 subunit.


Blood ◽  
1994 ◽  
Vol 84 (3) ◽  
pp. 898-903
Author(s):  
M Cohen-Solal ◽  
C Valentin ◽  
F Plassa ◽  
G Guillemin ◽  
F Danze ◽  
...  

Phosphoglycerate kinase (PGK) deficiency is generally associated with chronic hemolytic anemia, although it can be accompanied by either mental retardation or muscular disease. Genomic DNAs of two PGK- deficient patients previously described in France were sequenced directly after polymerase chain reaction amplification. The PGK Creteil variant arises from a G-->A nucleotide interchange at position 1022 in cDNA (exon 9), resulting in amino acid substitution 314 Asp-->Asn in the C-terminal domain, which contains the nucleotide binding site. It is associated with rhabdomyolysis crises but not with hemolysis or mental retardation. In the other case, which is associated with chronic hemolytic anemia and mental retardation (PGK Amiens), an A-->T nucleotide interchange was found at position 571 in cDNA (exon 5); this leads to amino acid substitution 163 Asp-->Val in the N-terminal domain, which contains the catalytic site for phosphoglycerate binding. These results corroborate the kinetic data observed. In the two cases, the mutations are distinct from others previously reported and no significant relationship could be observed between the location of the amino acid substitution and its clinical consequences.


2006 ◽  
Vol 50 (1) ◽  
pp. 253-254 ◽  
Author(s):  
Tomoko Sakata ◽  
Jun Takakura ◽  
Hiroyuki Miyakubo ◽  
Yuko Osada ◽  
Rieko Wada ◽  
...  

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