The yeast alpha 1 and MCM1 proteins bind a single strand of their duplex DNA recognition site

1992 ◽  
Vol 12 (8) ◽  
pp. 3573-3582
Author(s):  
E J Grayhack

The yeast cell type regulator alpha 1 cooperates with a constitutive factor, MCM1 protein, to recognize the promoter and activate transcription of several alpha-specific genes. I show here that the alpha 1 and MCM1 proteins bind specifically to one of the two strands of their recognition sequence. This single-strand-binding activity shares several characteristics with the duplex-binding properties of these proteins: (i) the MCM1 protein binds alone to single-stranded and duplex sequences of both the alpha-specific (P'Q) and a-specific (P) binding sites; (ii) the alpha 1 protein requires both the MCM1 protein and the Q sequence to bind either single-stranded or duplex DNA; (iii) the alpha 1 protein stimulates binding of the MCM1 protein to both single-stranded and duplex DNAs; and (iv) the affinities of the proteins for single-stranded and duplex DNAs are comparable.

1992 ◽  
Vol 12 (8) ◽  
pp. 3573-3582 ◽  
Author(s):  
E J Grayhack

The yeast cell type regulator alpha 1 cooperates with a constitutive factor, MCM1 protein, to recognize the promoter and activate transcription of several alpha-specific genes. I show here that the alpha 1 and MCM1 proteins bind specifically to one of the two strands of their recognition sequence. This single-strand-binding activity shares several characteristics with the duplex-binding properties of these proteins: (i) the MCM1 protein binds alone to single-stranded and duplex sequences of both the alpha-specific (P'Q) and a-specific (P) binding sites; (ii) the alpha 1 protein requires both the MCM1 protein and the Q sequence to bind either single-stranded or duplex DNA; (iii) the alpha 1 protein stimulates binding of the MCM1 protein to both single-stranded and duplex DNAs; and (iv) the affinities of the proteins for single-stranded and duplex DNAs are comparable.


1981 ◽  
Vol 91 (1) ◽  
pp. 163-173 ◽  
Author(s):  
S. W. MANLEY ◽  
J. R. BOURKE

Binding of 125I-labelled bovine TSH to crude membrane fractions of human thyroid tissue was a saturable, hormonally specific process which yielded non-linear Scatchard plots with limiting affinities of approximately 109 and 107l/mol. Binding activity in membranes was soluble in Triton X-100, was inhibited specifically by immunoglobulins from patients with Graves's disease, and was increased by the beta-blocking drug, propranolol. In contrast, purified nuclear preparations showed a predominance of lower affinity binding, and their binding activity was insoluble in Triton and insensitive to immunoglobulins from patients with Graves's disease and to propranolol. Tryptic digestion liberated only low affinity binding activity from membranes or nuclei. It was concluded that human thyroid tissue contains independent classes of TSH-binding sites, which differ in their chemical, immunological and hormone-binding properties.


2003 ◽  
Vol 77 (11) ◽  
pp. 6274-6283 ◽  
Author(s):  
Olivier Leupin ◽  
Séverine Bontron ◽  
Michel Strubin

ABSTRACT The UV-damaged DNA-binding activity protein (UV-DDB) consists of two subunits, DDB1 and DDB2, and functions in DNA repair and cell cycle regulation. The DDB1 subunit is a target for the hepatitis B virus X protein (HBx). Binding of HBx to DDB1 interferes with cell growth and viability in culture and has been implicated in the establishment of viral infection. DDB1 also interacts with the V proteins encoded by several paramyxoviruses including simian virus 5 (SV5), which prevent interferon signaling by targeting either STAT1 or STAT2 proteins for proteolysis. The role of V binding to DDB1, however, remains unclear. Here we show that the V protein of SV5 (SV5-V) and HBx exhibit strikingly similar DDB1 binding properties. Thus, SV5-V and HBx bind to DDB1 in a mutually exclusive manner, and SV5-V shares with HBx the ability to enhance the steady-state levels of DDB1 and to inhibit its association with DDB2. Yet only HBx induces cell death, and SV5-V can prevent HBx from doing so by blocking its interaction with DDB1. Binding of SV5-V to DDB1 may serve another function, since SV5-V shows a decreased ability to induce STAT1 degradation in cells expressing reduced amounts of DDB1. These findings demonstrate that HBx performs a unique function through its association with DDB1 for which SV5-V cannot substitute and suggest that SV5-V and HBx have evolved to bind DDB1 to achieve distinct functions, both by a mechanism that does not involve DDB2.


Nature ◽  
10.1038/16833 ◽  
1999 ◽  
Vol 397 (6717) ◽  
pp. 310-310 ◽  
Author(s):  
Stefan U. Åström ◽  
Sara M. Okamura ◽  
Jasper Rine
Keyword(s):  

1987 ◽  
Vol 248 (1) ◽  
pp. 167-171 ◽  
Author(s):  
Y Hiller ◽  
J M Gershoni ◽  
E A Bayer ◽  
M Wilchek

A commercially available, purified preparation of avidin was found to comprise two polypeptide bands (Mr 18,000 and Mr 15,500 respectively). Both bands bound biotin as assessed by biotin overlays of protein blots. The Mr 15,500 polypeptide was found to differ from the Mr 18,000 polypeptide only in its sugar content. When the commercial preparation was applied to a concanavalin A affinity column, the glycosylated forms were retarded as expected, and homotypic nonglycosylated avidin tetramers which failed to bind selectively to the column were collected in the effluent. The biotin-binding properties of the nonglycosylated avidin were equivalent to those obtained for the native (glycosylated) avidin molecule, indicating that the oligosaccharide moiety is not essential for the binding activity.


1989 ◽  
Vol 120 (2) ◽  
pp. 180-186 ◽  
Author(s):  
Lee M. Sanford

Abstract. The testes of the ram become more responsive to LH stimulation following immunoneutralization of endogenous estradiol. The possibility that testosterone secretion is facilitated by increased LH-binding activity in the testes was investigated in the present study conducted with adult Dorset × Leicester × Suffolk rams during the time of testicular recrudescence. Patterns of episodic LH release and testosterone secretion (days –5, 10 and 24) and LH-binding activity in testicular biopsy samples (days –1, 14 and 28) were assessed on the days indicated relative to the onset of passive immunization and the establishment of relatively low titres (~1:200) of estradiol antiserum. During the experimental period, mean serum testosterone concentration increased by approximately 150% for the immunized rams as basal concentration and pulse amplitude increased, while all characteristics of testosterone secretion remained unchanged for the nonimmunized rams. Characteristics of LH release and the concentration of LH-binding sites in the testes, however, were always similar for both groups of rams. Further, group differences in FSH and PRL secretion and in the concentration of testicular FSH-binding sites did not occur. These results provide evidence for an estradiol direct (gonadotropin independent) negativefeedback component in the regulation of Leydig cell function in the ram.


1998 ◽  
Vol 17 (18) ◽  
pp. 5466-5476 ◽  
Author(s):  
Matthew Newman ◽  
Keith Lunnen ◽  
Geoffrey Wilson ◽  
John Greci ◽  
Ira Schildkraut ◽  
...  

2021 ◽  
Vol 141 (5) ◽  
pp. 697-708
Author(s):  
Yang Shi ◽  
Alexey G. Murzin ◽  
Benjamin Falcon ◽  
Alexander Epstein ◽  
Jonathan Machin ◽  
...  

AbstractTau and Aβ assemblies of Alzheimer’s disease (AD) can be visualized in living subjects using positron emission tomography (PET). Tau assemblies comprise paired helical and straight filaments (PHFs and SFs). APN-1607 (PM-PBB3) is a recently described PET ligand for AD and other tau proteinopathies. Since it is not known where in the tau folds PET ligands bind, we used electron cryo-microscopy (cryo-EM) to determine the binding sites of APN-1607 in the Alzheimer fold. We identified two major sites in the β-helix of PHFs and SFs and a third major site in the C-shaped cavity of SFs. In addition, we report that tau filaments from posterior cortical atrophy (PCA) and primary age-related tauopathy (PART) are identical to those from AD. In support, fluorescence labelling showed binding of APN-1607 to intraneuronal inclusions in AD, PART and PCA. Knowledge of the binding modes of APN-1607 to tau filaments may lead to the development of new ligands with increased specificity and binding activity. We show that cryo-EM can be used to identify the binding sites of small molecules in amyloid filaments.


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