scholarly journals Specific amino-acid residues in the N-terminus and TM3 implicated in channel function and oligomerization compatibility of connexin43

2003 ◽  
Vol 116 (15) ◽  
pp. 3189-3201 ◽  
Author(s):  
V. Lagree
Keyword(s):  
Amino Acid ◽  
Amino Acid Residues ◽  
Specific Amino Acid ◽  
Channel Function ◽  
N Terminus

scholarly journals Rapid resensitization of ASIC2a is conferred by three amino acid residues in the N-terminus

IBRO Reports ◽  
2019 ◽  
Vol 6 ◽  
pp. S427-S428
Author(s):  
Jae Seung Lee ◽  
Hae-Jin Kweon ◽  
Byung-Chang Suh ◽  
Hyosang Lee
Keyword(s):  
Amino Acid ◽  
Amino Acid Residues ◽  
N Terminus

scholarly journals Identification of critical amino acid residues in the regulatory N-terminal domain of PMEL

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Susan M. Mitchell ◽  
Morven Graham ◽  
Xinran Liu ◽  
Ralf M. Leonhardt
Keyword(s):  
Amino Acid ◽  
Pigment Cell ◽  
Specific Protein ◽  
Single Amino Acid ◽  
Amyloid Formation ◽  
Amino Acid Residues ◽  
Proteolytic Fragment ◽  
The Core ◽  
N Terminus ◽  
In Cis

AbstractThe pigment cell-specific protein PMEL forms a functional amyloid matrix in melanosomes onto which the pigment melanin is deposited. The amyloid core consists of a short proteolytic fragment, which we have termed the core-amyloid fragment (CAF) and perhaps additional parts of the protein, such as the PKD domain. A highly O-glycosylated repeat (RPT) domain also derived from PMEL proteolysis associates with the amyloid and is necessary to establish the sheet-like morphology of the assemblies. Excluded from the aggregate is the regulatory N-terminus, which nevertheless must be linked in cis to the CAF in order to drive amyloid formation. The domain is then likely cleaved away immediately before, during, or immediately after the incorporation of a new CAF subunit into the nascent amyloid. We had previously identified a 21 amino acid long region, which mediates the regulatory activity of the N-terminus towards the CAF. However, many mutations in the respective segment caused misfolding and/or blocked PMEL export from the endoplasmic reticulum, leaving their phenotype hard to interpret. Here, we employ a saturating mutagenesis approach targeting the motif at single amino acid resolution. Our results confirm the critical nature of the PMEL N-terminal region and identify several residues essential for PMEL amyloidogenesis.

scholarly journals Genetic Diversity of the cagA gene of Helicobacter pylori strains from Sudanese Patients with Different Gastroduodenal Diseases

2019 ◽  
Author(s):  
Hadeel Gassim Hassan ◽  
Abeer Babiker Idris ◽  
Mohamed A. Hassan ◽  
Hisham N. Altayb ◽  
Kyakonye Yasin ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Amino Acid ◽  
Novel Mutation ◽  
Amino Acid Residues ◽  
Specific Amino Acid ◽  
Gastrointestinal Malignancy ◽  
High Incidence ◽  
H Pylori ◽  
High Level ◽  
Chloride Method

AbstractBackgroundThere is an increase in the prevalence of Helicobacter pylori infection in Sudan, accompanied by a high incidence of upper gastrointestinal malignancy. The cytotoxin-associated gene cagA gene is a marker of a pathogenicity island (PAI) in H. pylori and plays a crucial role in determining the clinical outcome of Helicobacter infections.ObjectiveThis study aimed to determine the frequency and heterogeneity of the cagA gene of H. pylori and correlate the presence of cagA gene with clinical outcomes.Materials and methodsFifty endoscopy biopsies were collected from Fedail and Soba hospitals in Khartoum state. DNA was extracted using the Guanidine chloride method followed by PCR to amplify 16S rRNA and cagA gene of H. pylori using specific primers. DNA amplicons of cagA gene were purified and sequenced. Bioinformatics and statistical analysis were done to characterize and to test the association between cagA gene and gastric complications.ResultsCagA gene was detected in 20/37(54%) of the samples that were found positive for H. pylori. There was no association between endoscopy finding and the presence of the cagA gene (p = 0.225). Specific amino acid variations were found at seven loci related to strains from a patient with duodenitis, gastric ulcer, and gastric atrophy (R448H, T457K, S460L, IT463-464VA, D470E, A482Q, KNV490-491-492TKT) while mutations in cancerous strain were A439P, T457P, and H500Y.ConclusionDisease-specific variations of cagA of H. pylori strains, in the region of amino acid residues 428-510, were evident among Sudanese patients with different gastroduodenal diseases. A novel mutation (K458N) was detected in a patient with duodenitis, which affects the positive electrostatic surface of cagA. Phylogenetic analysis showed a high level of diversity of cagA from Sudanese H. pylori strains.

A Mutation in the  Subunit of the Platelet Integrin IIbβ3 Identifies a Novel Region Important for Ligand Binding

Blood ◽  
1999 ◽  
Vol 93 (3) ◽  
pp. 918-924 ◽  
Author(s):  
Eileen Collins Tozer ◽  
Elizabeth K. Baker ◽  
Mark H. Ginsberg ◽  
Joseph C. Loftus
Keyword(s):  
Amino Acid ◽  
Ligand Binding ◽  
Single Amino Acid ◽  
Chimeric Receptor ◽  
Amino Acid Residues ◽  
Genetic Approach ◽  
Specific Amino Acid ◽  
Transfected Cells ◽  
Binding Function ◽  
A Cell

Abstract An unbiased genetic approach was used to identify a specific amino acid residue in the IIb subunit important for the ligand binding function of the integrin IIbβ. Chemically mutagenized cells were selected by flow cytometry based on their inability to bind the ligand mimetic antibody PAC1 and a cell line containing a single amino acid substitution in IIb at position 224 (D→V) was identified. Although well expressed on the surface of transfected cells, IIbD224Vβ3 as well as IIbD224Aβ3 did not bind IIbβ3-specific ligands or a RGD peptide, a ligand shared in common with vβ3. Insertion of exon 5 of IIb, residues G193-W235, into the backbone of the v subunit did not enable the chimeric receptor to bind IIbβ3-specific ligands. However, the chimeric receptor was still capable of binding to a RGD affinity matrix. IIbD224 is not well conserved among other integrin  subunits and is located in a region of significant variability. In addition, amino acid D224 lies within a predicted loop of the recently proposed β-propeller model for integrin  subunits and is adjacent to a loop containing amino acid residues previously implicated in receptor function. These data support a role for this region in ligand binding function of the IIbβ3 receptor.

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