scholarly journals The C-terminus of connexin43 adopts different conformations in the Golgi and gap junction as detected with structure-specific antibodies

2007 ◽  
Vol 408 (3) ◽  
pp. 375-385 ◽  
Author(s):  
Gina E. Sosinsky ◽  
Joell L. Solan ◽  
Guido M. Gaietta ◽  
Lucy Ngan ◽  
Grace J. Lee ◽  
...  
Keyword(s):  
Gap Junction ◽  
Tertiary Structure ◽  
Mutational Analysis ◽  
Peptide Mapping ◽  
Rat Kidney ◽  
Intracellular Localization ◽  
Protein Protein Interaction ◽  
Binding Domains ◽  
C Terminus ◽  
Junction Protein

The C-terminus of the most abundant and best-studied gap-junction protein, connexin43, contains multiple phosphorylation sites and protein-binding domains that are involved in regulation of connexin trafficking and channel gating. It is well-documented that SDS/PAGE of NRK (normal rat kidney) cell lysates reveals at least three connexin43-specific bands (P0, P1 and P2). P1 and P2 are phosphorylated on multiple, unidentified serine residues and are found primarily in gap-junction plaques. In the present study we prepared monoclonal antibodies against a peptide representing the last 23 residues at the C-terminus of connexin43. Immunofluorescence studies showed that one antibody (designated CT1) bound primarily to connexin43 present in the Golgi apparatus, whereas the other antibody (designated IF1) labelled predominately connexin43 present in gap junctions. CT1 immunoprecipitates predominantly the P0 form whereas IF1 recognized all three bands. Peptide mapping, mutational analysis and protein–protein interaction experiments revealed that unphosphorylated Ser364 and/or Ser365 are critical for CT1 binding. The IF1 paratope binds to residues Pro375–Asp379 and requires Pro375 and Pro377. These proline residues are also necessary for ZO-1 interaction. These studies indicate that the conformation of Ser364/Ser365 is important for intracellular localization, whereas the tertiary structure of Pro375–Asp379 is essential in targeting and regulation of gap junctional connexin43.

scholarly journals Phosphotyrosine-dependent interaction of SHC and insulin receptor substrate 1 with the NPEY motif of the insulin receptor via a novel non-SH2 domain.

1995 ◽  
Vol 15 (5) ◽  
pp. 2500-2508 ◽  
Author(s):  
T A Gustafson ◽  
W He ◽  
A Craparo ◽  
C D Schaub ◽  
T J O'Neill
Keyword(s):  
Insulin Receptor ◽  
Mutational Analysis ◽  
Sh2 Domain ◽  
Binding Domain ◽  
Homologous Region ◽  
Juxtamembrane Domain ◽  
Atp Binding Site ◽  
Protein Protein Interaction ◽  
Binding Domains ◽  
Src Homology 2 Domain

The SHC proteins have been implicated in insulin receptor (IR) signaling. In this study, we used the sensitive two-hybrid assay of protein-protein interaction to demonstrate that SHC interacts directly with the IR. The interaction is mediated by SHC amino acids 1 to 238 and is therefore independent of the Src homology 2 domain. The interaction is dependent upon IR autophosphorylation, since the interaction is eliminated by mutation of the IR ATP-binding site. In addition, mutational analysis of the Asn-Pro-Glu-Tyr (NPEY) motif within the juxtamembrane domain of the IR showed the importance of the Asn, Pro, and Tyr residues to both SHC and IR substrate 1 (IRS-1) binding. We conclude that SHC interacts directly with the IR and that phosphorylation of Tyr-960 within the IR juxtamembrane domain is necessary for efficient interaction. This interaction is highly reminiscent of that of IRS-1 with the IR, and we show that the SHC IR-binding domain can substitute for that of IRS-1 in yeast and COS cells. We identify a homologous region within the IR-binding domains of SHC and IRS-1, which we term the SAIN (SHC and IRS-1 NPXY-binding) domain, which may explain the basis of these interactions. The SAIN domain appears to represent a novel motif which is able to interact with autophosphorylated receptors such as the IR.

scholarly journals Crystal structure of N-terminal IFIT3 reveals domain-swapping dimerization

2014 ◽  
Vol 70 (a1) ◽  
pp. C1629-C1629
Author(s):  
Yazan Abbas ◽  
Irene Yuning Xie ◽  
Bhushan Nagar
Keyword(s):  
Crystal Structure ◽  
Complex Formation ◽  
Mutational Analysis ◽  
Structural Information ◽  
Domain Swapping ◽  
Tetratricopeptide Repeat ◽  
Alpha Helices ◽  
Protein Protein Interaction ◽  
C Terminus ◽  
General Protein

IFIT proteins are interferon-inducible, antiviral effectors that form a multiprotein complex with the ability to recognize markers of viral infection and subsequently restrict viruses. IFIT1, IFIT2 and IFIT3 are at the heart of the complex, interacting with each other and several host factors, forming what is known as the 'IFIT interactome'. Central to their ability to mediate complex formation is the tetratricopeptide repeat (TPR) motif, a general protein-protein interaction module comprising a pair of antiparallel alpha helices. Additionally The TPR motifs of IFIT proteins have the unique ability to recognize RNA. Whereas IFIT1 interacts with virus derived ssRNA, IFIT2 has been shown to interact with dsRNA; IFIT3 is not known to bind RNA. Importantly, structural information is available for the N-terminal domain of IFIT1 and full-length IFIT2, but not for IFIT3. To gain insight into the mechanisms regulating complex formation, we are targeting the structure of human IFIT3 before incorporation into the IFIT complex. To that end, we have determined a low resolution crystal structure of N-terminal IFIT3, which reveals a domain swapped dimer. Notably, IFIT3 dimerization is similar to IFIT2, but distinct from IFIT1, which dimerizes via its C-terminus. Sequence conservation and structural analysis suggest that IFIT2 and IFIT3 evolved a similar mechanism for domain swapping. We propose that IFIT2 and IFIT3 may interact by forming domain swapped heterodimers. Current work is aimed at investigating the mechanisms of domain swapping via mutational analysis, and determining the structure of C-terminal human IFIT3.

The Morphology of the Rat Kidney Following Folic Acid Administration

1970 ◽  
Vol 28 ◽  
pp. 200-201
Author(s):  
Aline Byrnes ◽  
Elsa E. Ramos ◽  
Minoru Suzuki ◽  
E.D. Mayfield
Keyword(s):  
Folic Acid ◽  
De Novo ◽  
Specific Activity ◽  
Rat Kidney ◽  
Present Report ◽  
Intracellular Localization ◽  
Male Rats ◽  
Renal Hypertrophy ◽  
Electron Microscopic ◽  
Biochemical Alterations

Renal hypertrophy was induced in 100 g male rats by the injection of 250 mg folic acid (FA) dissolved in 0.3 M NaHCO3/kg body weight (i.v.). Preliminary studies of the biochemical alterations in ribonucleic acid (RNA) metabolism of the renal tissue have been reported recently (1). They are: RNA content and concentration, orotic acid-c14 incorporation into RNA and acid soluble nucleotide pool, intracellular localization of the newly synthesized RNA, and the specific activity of enzymes of the de novo pyrimidine biosynthesis pathway. The present report describes the light and electron microscopic observations in these animals. For light microscopy, kidney slices were fixed in formalin, embedded, sectioned, and stained with H & E and PAS.

scholarly journals Deamidation and glycation of a Bacillus licheniformis α-amylase during industrial fermentation can improve detergent wash performance

Amylase ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 38-49
Author(s):  
Connie Pontoppidan ◽  
Svend G. Kaasgaard ◽  
Carsten P. Sønksen ◽  
Carsten Andersen ◽  
Birte Svensson
Keyword(s):  
Bacillus Licheniformis ◽  
Mutational Analysis ◽  
Peptide Mapping ◽  
Substrate Binding ◽  
Carbohydrate Binding ◽  
Surface Binding ◽  
Lysine Residues ◽  
Tandem Mass Spectrometric ◽  
Binding Cleft ◽  
Household Detergents

Abstract The industrial thermostable Bacillus licheniformis α-amylase (BLA) has wide applications, including in household detergents, and efforts to improve its performance are continuously ongoing. BLA during the industrial production is deamidated and glycated resulting in multiple forms with different isoelectric points. Forty modified positions were identified by tandem mass spectrometric peptide mapping of BLA forms separated by isoelectric focusing. These modified 12 asparagine, 9 glutamine, 8 arginine and 11 lysine residues are mostly situated on the enzyme surface and several belong to regions involved in stability, activity and carbohydrate binding. Eight residues presumed to interact with starch at the active site and surface binding sites (SBSs) were subjected to mutational analysis. Five mutants mimicking deamidation (N→D, Q→E) at the substrate binding cleft showed moderate to no effect on thermostability and k cat and K M for maltoheptaose and amylose. Notably, the mutations improved laundry wash efficiency in detergents at pH 8.5 and 10.0. Replacing three reducing sugar reactive side chains (K→M, R→L) at a distant substrate binding region and two SBSs enhanced wash performance especially in liquid detergent at pH 8.5, slightly improved enzymatic activity and maintained thermostability. Wash performance was most improved (5-fold) for the N265D mutant near substrate binding subsite +3.

scholarly journals In silico characterization and structural modeling of bacterial metalloprotease of family M4

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Rajnee Hasan ◽  
Md. Nazmul Haq Rony ◽  
Rasel Ahmed
Keyword(s):  
Drug Targets ◽  
Active Sites ◽  
Pathogenic Bacteria ◽  
Tertiary Structure ◽  
Transmembrane Helix ◽  
Confidence Score ◽  
Potential Drug ◽  
Protein Protein Interaction ◽  
Industrial Level ◽  
Potential Drug Targets

Abstract Background The M4 family of metalloproteases is comprised of a large number of zinc-containing metalloproteases. A large number of these enzymes are important virulence factors of pathogenic bacteria and therefore potential drug targets. Whereas some enzymes have potential for biotechnological applications, the M4 family of metalloproteases is known almost exclusively from bacteria. The aim of the study was to identify the structure and properties of M4 metalloprotease proteins. Results A total of 31 protein sequences of M4 metalloprotease retrieved from UniProt representing different species of bacteria have been characterized for various physiochemical properties. They were thermostable, hydrophillic protein of a molecular mass ranging from 38 to 66 KDa. Correlation on the basis of both enzymes and respective genes has also been studied by phylogenetic tree. B. cereus M4 metalloprotease (PDB ID: 1NPC) was selected as a representative species for secondary and tertiary structures among the M4 metalloprotease proteins. The secondary structure displaying 11 helices (H1-H11) is involved in 15 helix-helix interactions, while 4 β-sheet motifs composed of 15 β-strands in PDBsum. Possible disulfide bridges were absent in most of the cases. The tertiary structure of B. cereus M4 metalloprotease was validated by QMEAN4 and SAVES server (Ramachandran plot, verify 3D, and ERRAT) which proved the stability, reliability, and consistency of the tertiary structure of the protein. Functional analysis was done in terms of membrane protein topology, disease-causing region prediction, proteolytic cleavage sites prediction, and network generation. Transmembrane helix prediction showed absence of transmembrane helix in protein. Protein-protein interaction networks demonstrated that bacillolysin of B. cereus interacted with ten other proteins in a high confidence score. Five disorder regions were identified. Active sites analysis showed the zinc-binding residues—His-143, His-147, and Glu-167, with Glu-144 acting as the catalytic residues. Conclusion Moreover, this theoretical overview will help researchers to get a details idea about the protein structure and it may also help to design enzymes with desirable characteristics for exploiting them at industrial level or potential drug targets.

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