scholarly journals The Amino-terminal One-third of Defines the Ligand Recognition Specificity of Integrin

1996 ◽  
Vol 271 (4) ◽  
pp. 2033-2039 ◽  
Author(s):  
Joseph C. Loftus ◽  
Carol E. Halloran ◽  
Mark H. Ginsberg ◽  
Larry P. Feigen ◽  
Jeffery A. Zablocki ◽  
...  
Biochemistry ◽  
2015 ◽  
Vol 54 (6) ◽  
pp. 1408-1420 ◽  
Author(s):  
Nataly P. Podolnikova ◽  
Andriy V. Podolnikov ◽  
Thomas A. Haas ◽  
Valeryi K. Lishko ◽  
Tatiana P. Ugarova

1996 ◽  
Vol 271 (17) ◽  
pp. 10365-10371 ◽  
Author(s):  
Kazuhisa Suehiro ◽  
Jeffrey W. Smith ◽  
Edward F. Plow

Genetics ◽  
1996 ◽  
Vol 144 (3) ◽  
pp. 861-870
Author(s):  
J Sakai ◽  
N Kleckner

Abstract Tn10 transposition requires IS10 transposase and essential sequences at the two ends of the element. Mutations in terminal basepairs 6–13 confer particularly strong transposition defects. We describe here the identification of transposase mutations that suppress the transposition defects of such terminus mutations. These mutations are named “SEM” for suppression of ends mutations. All of the SEM mutations suppress more than a single terminus mutation and thus are not simple alterations of transposase/end recognition specificity. The mutations identified fall into two classes on the basis of genetic tests, location within the protein and nature of the amino acid substitution. Class I mutations, which are somewhat allele specific, appear to define a small structural and functional domain of transposase in which hydrophobic interactions are important at an intermediate stage of the transposition reaction, after an effective interaction between the ends but before transposon excision. Class II mutations, which are more general in their effects, occur at a single residue in a small noncritical amino-terminal proteolytic domain of transposase and exert their affects by altering a charge interaction; these mutations may affect act early in the reaction, before or during establishment of an effective interaction between the ends.


1994 ◽  
Vol 124 (4) ◽  
pp. 609-618 ◽  
Author(s):  
GS Kansas ◽  
KB Saunders ◽  
K Ley ◽  
A Zakrzewicz ◽  
RM Gibson ◽  
...  

The selectin family of adhesion molecules mediates the initial interactions of leukocytes with endothelium. The extracellular region of each selectin contains an amino-terminal C-type lectin domain, followed by an EGF-like domain and multiple short consensus repeat units (SCR). Previous studies have indirectly suggested a role for each of the extracellular domains of the selectins in cell adhesion. In this study, a panel of chimeric selectins created by exchange of domains between L- and P-selectin was used to directly examine the role of the extracellular domains in cell adhesion. Exchange of only the lectin domains between L- and P-selectin conferred the adhesive and ligand recognition functions of the lectin domain of the parent molecule. However, chimeric selectins which contained both the lectin domain of L-selectin and the EGF-like domain of P-selectin exhibited dual ligand-binding specificity. These chimeric proteins supported adhesion both to myeloid cells and to high endothelial venules (HEV) of lymph nodes and mesenteric venules in vivo. Exchange of the SCR domains had no detectable effect on receptor function or specificity. Thus, the EGF-like domain of P-selectin may play a direct role in ligand recognition and leukocyte adhesion mediated by P-selectin, with the lectin plus EGF-like domains collectively forming a functional ligand recognition unit.


2000 ◽  
Vol 6 (2) ◽  
pp. 130-139 ◽  
Author(s):  
Duncan J. Campbell ◽  
Kenneth I. Mitchelhill ◽  
Stephen M. Schlicht ◽  
Russell J. Booth

1990 ◽  
Vol 63 (02) ◽  
pp. 193-203 ◽  
Author(s):  
John R Shainoff ◽  
Deborah J Stearns ◽  
Patricia M DiBello ◽  
Youko Hishikawa-Itoh

SummaryThe studies reported here probe the existence of a receptor-mediated mode of fibrin-binding by macrophages that is associated with the chemical change underlying the fibrinogen-fibrin conversion (the release of fibrinopeptides from the amino-terminal domain) without depending on fibrin-aggregation. The question is pursued by 1) characterization of binding in relation to fibrinopeptide content of both the intact protein and the CNBr-fragment comprising the amino-terminal domain known as the NDSK of the protein, 2) tests of competition for binding sites, and 3) photo-affinity labeling of macrophage surface proteins. The binding of intact monomers of types lacking either fibrinopeptide A alone (α-fibrin) or both fibrinopeptides A and B (αβ-fibrin) by peritoneal macrophages is characterized as proceeding through both a fibrin-specific low density/high affinity (BMAX ≃ 200–800 molecules/cell, KD ≃ 10−12 M) interaction that is not duplicated with fibrinogen, and a non-specific high density/low affinity (BMAX ≥ 105 molecules/cell, KD ≥ 10−6 M) interaction equivalent to the weak binding of fibrinogen. Similar binding characteristics are displayed by monocyte/macrophage cell lines (J774A.1 and U937) as well as peritoneal macrophages towards the NDSK preparations of these proteins, except for a slightly weaker (KD ≃ 10−10 M) high-affinity binding. The high affinity binding of intact monomer is inhibitable by fibrin-NDSK, but not fibrinogen-NDSK. This binding appears principally dependent on release of fibrinopeptide-A, because a species of fibrin (β-fibrin) lacking fibrinopeptide-B alone undergoes only weak binding similar to that of fibrinogen. Synthetic Gly-Pro-Arg and Gly-His-Arg-Pro corresponding to the N-termini of to the α- and the β-chains of fibrin both inhibit the high affinity binding of the fibrin-NDSKs, and the cell-adhesion peptide Arg-Gly-Asp does not. Photoaffinity-labeling experiments indicate that polypeptides with elec-trophoretically estimated masses of 124 and 187 kDa are the principal membrane components associated with specifically bound fibrin-NDSK. The binding could not be up-regulated with either phorbol myristyl acetate, interferon gamma or ADP, but was abolished by EDTA and by lipopolysaccharide. Because of the low BMAX, it is suggested that the high-affinity mode of binding characterized here would be too limited to function by itself in scavenging much fibrin, but may act cooperatively with other, less limited modes of fibrin binding.


1993 ◽  
Vol 70 (05) ◽  
pp. 867-872 ◽  
Author(s):  
Dingeman C Rijken ◽  
Gerard A W de Munk ◽  
Annie F H Jie

SummaryIn order to define the possible effects of heparin on the fibrinolytic system under physiological conditions, we studied the interactions of this drug with plasminogen and its activators at various ionic strengths. As reported in recent literature, heparin stimulated the activation of Lys-plasminogen by high molecular weight (HMW) and low molecular weight (LMW) two-chain urokinase-type plasminogen activator (u-PA) and two-chain tissue-type plasminogen activator (t-PA) 10- to 17-fold. Our results showed, however, that this stimulation only occurred at low ionic strength and was negligible at a physiological salt concentration. Direct binding studies were performed using heparin-agarose column chromatography. The interaction between heparin and Lys-plasminogen appeared to be salt sensitive, which explains at least in part why heparin did not stimulate plasminogen activation at 0.15 M NaCl. The binding of u-PA and t-PA to heparinagarose was less salt sensitive. Results were consistent with heparin binding sites on both LMW u-PA and the amino-terminal part of HMW u-PA. Single-chain t-PA bound more avidly than two-chain t-PA. The interactions between heparin and plasminogen activators can occur under physiological conditions and may modulate the fibrinolytic system.


1996 ◽  
Vol 75 (02) ◽  
pp. 313-317 ◽  
Author(s):  
D J Kim ◽  
A Girolami ◽  
H L James

SummaryNaturally occurring plasma factor XFriuli (pFXFr) is marginally activated by both the extrinsic and intrinsic coagulation pathways and has impaired catalytic potential. These studies were initiated to obtain confirmation that this molecule is multi-functionally defective due to the substitution of Ser for Pro at position 343 in the catalytic domain. By the Nelson-Long site-directed mutagenesis procedure a construct of cDNA in pRc/CMV was derived for recombinant factor XFriuli (rFXFr) produced in human embryonic (293) kidney cells. The rFXFr was purified and shown to have a molecular size identical to that of normal plasma factor X (pFX) by gel electrophoretic, and amino-terminal sequencing revealed normal processing cleavages. Using recombinant normal plasma factor X (rFXN) as a reference, the post-translational y-carboxy-glutamic acid (Gla) and (β-hydroxy aspartic acid (β-OH-Asp) content of rFXFr was over 85% and close to 100%, respectively, of expected levels. The specific activities of rFXFr in activation and catalytic assays were the same as those of pFXFr. Molecular modeling suggested the involvement of a new H-bond between the side-chains of Ser-343 and Thr-318 as they occur in anti-parallel (3-pleated sheets near the substrate-binding pocket of pFXFr. These results support the conclusion that the observed mutation in pFXFr is responsible for its dysfunctional activation and catalytic potentials, and that it accounts for the moderate bleeding tendency in the homozygous individuals who possess this variant procoagulant.


1993 ◽  
Vol 69 (04) ◽  
pp. 351-360 ◽  
Author(s):  
Masahiro Murakawa ◽  
Takashi Okamura ◽  
Takumi Kamura ◽  
Tsunefumi Shibuya ◽  
Mine Harada ◽  
...  

SummaryThe partial amino acid sequences of fibrinogen Aα-chains from five mammalian species have been inferred by means of the polymerase chain reaction (PCR). From the genomic DNA of the rhesus monkey, pig, dog, mouse and Syrian hamster, the DNA fragments coding for α-C domains in the Aα-chains were amplified and sequenced. In all species examined, four cysteine residues were always conserved at the homologous positions. The carboxy- and amino-terminal portions of the α-C domains showed a considerable homology among the species. However, the sizes of the middle portions, which corresponded to the internal repeat structures, showed an apparent variability because of several insertions and/or deletions. In the rhesus monkey, pig, mouse and Syrian hamster, 13 amino acid tandem repeats fundamentally similar to those in humans and the rat were identified. In the dog, however, tandem repeats were found to consist of 18 amino acids, suggesting an independent multiplication of the canine repeats. The sites of the α-chain cross-linking acceptor and α2-plasmin inhibitor cross-linking donor were not always evolutionally conserved. The arginyl-glycyl-aspartic acid (RGD) sequence was not found in the amplified region of either the rhesus monkey or the pig. In the canine α-C domain, two RGD sequences were identified at the homologous positions to both rat and human RGD S. In the Syrian hamster, a single RGD sequence was found at the same position to that of the rat. Triplication of the RGD sequences was seen in the murine fibrinogen α-C domain around the homologous site to the rat RGDS sequence. These findings are of some interest from the point of view of structure-function and evolutionary relationships in the mammalian fibrinogen Aα-chains.


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