Reaction of α-tubulin with lodotyrosines catalyzed by tubulin: Tyrosine ligase: Carboxy-terminal labeling of tubulin with [125I]monoiodotyrosine

1990 ◽  
Vol 184 (2) ◽  
pp. 325-329 ◽  
Author(s):  
Marcel Joniau ◽  
Katleen Coudijzer ◽  
Marcel De Cuyper
Keyword(s):  
Tubulin Tyrosine Ligase ◽  
Carboxy Terminal

scholarly journals Tubulin-tyrosine ligase has a binding site on beta-tubulin: a two-domain structure of the enzyme

1987 ◽  
Vol 104 (4) ◽  
pp. 1059-1067 ◽  
Author(s):  
J Wehland ◽  
K Weber
Keyword(s):  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Enzymatic Activity ◽  
Binding Site ◽  
Gradient Centrifugation ◽  
Beta Tubulin ◽  
Alpha Tubulin ◽  
Alpha Beta ◽  
Tubulin Tyrosine Ligase ◽  
Carboxy Terminal

Tubulin-tyrosine ligase and alpha beta-tubulin form a tight complex which is conveniently monitored by glycerol gradient centrifugation. Using two distinct ligase monoclonal antibodies, several subunit-specific tubulin monoclonal antibodies, and chemical cross-linking, a ligase-binding site was identified on beta-tubulin. This site is retained when the carboxy-terminal domains of both tubulin subunits are removed by subtilisin treatment. The ligase-tubulin complex is also formed when ligase is added to alpha beta-tubulin carrying the monoclonal antibody YL 1/2 which binds only to the carboxyl end of tyrosinated alpha-tubulin. The beta-tubulin-binding site described here explains the extreme substrate specificity of ligase, which does not act on other cellular proteins or carboxy-terminal peptides derived from detyrosinated alpha-tubulin. Differential accessibility of this site in tubulin and in microtubules seems to explain why ligase acts preferentially on unpolymerized tubulin. Ligase exposed to V8-protease is converted to a nicked derivative. This is devoid of enzymatic activity but still forms the complex with tubulin. Gel electrophoresis documents both 30- and a 14-kD domains, each which is immunologically and biochemically distinct and seems to cover the entire molecule. The two domains interact tightly under physiological conditions. The 30-kD domain carries the binding sites for beta-tubulin and ATP. The 14-kD domain can possibly form an additional part of the catalytic site as it harbors the epitope for the monoclonal antibody ID3 which inhibits enzymatic activity but not the formation of the ligase-tubulin complex.

Inhibition of Platelet Adhesion to Fibrin(ogen) in Flowing Whole Blood by Arg-Gly-Asp and Fibrinogen γ-Chain Carboxy Terminal Peptides

1992 ◽  
Vol 68 (06) ◽  
pp. 694-700 ◽  
Author(s):  
Roy R Hantgan ◽  
Silvia C Endenburg ◽  
I Cavero ◽  
Gérard Marguerie ◽  
André Uzan ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Integrin Receptor ◽  
Shear Rates ◽  
Perfusion Chamber ◽  
Receptor Recognition ◽  
Adhesive Interactions ◽  
Coated Surfaces ◽  
Carboxy Terminal

SummaryWe have employed synthetic peptides with sequences corresponding to the integrin receptor-recognition regions of fibrinogen as inhibitors of platelet aggregation and adhesion to fibrinogen-and fibrin-coated surfaces in flowing whole blood, using a rectangular perfusion chamber at wall shear rates of 300 s–1 and 1,300 s–1. D-RGDW caused substantial inhibition of platelet aggregation and adhesion to fibrinogen and fibrin at both shear rates, although it was least effective at blocking platelet adhesion to fibrin at 300 s–1. RGDS was a weaker inhibitor, and produced a biphasic dose-response curve; SDRG was inactive. HHLGGAK-QAGDV partially inhibited platelet aggregation and adhesion to fibrin(ogen) at both shear rates. These results support the identification of an RGD-specific receptor, most likely the platelet integrin glycoprotein IIb: III a, as the primary receptor responsible for platelet: fibrin(ogen) adhesive interactions under flow conditions, and indicate that platelet adhesion to surface bound fibrin(ogen) is stabilized by multivalent receptor-ligand contacts.

The Ability of Fibrinogens, FI and FII, to Support ADP- Induced Platelet Aggregation

1983 ◽  
Vol 50 (02) ◽  
pp. 527-529 ◽  
Author(s):  
H M Phillips ◽  
A Mansouri ◽  
C A Perry
Keyword(s):  
Platelet Aggregation ◽  
Terminal Portion ◽  
Hepes Buffer ◽  
Carboxy Terminal

SummaryFibrinogen plays an integral part in ADP-induced platelet aggregation. Controversy exists in regard to the role of the carboxy termini of fibrinogen Aa chains in this reaction. We have attempted to clarify this problem in view of the availability of a highly purified FII fibrinogen fraction. Kabi fibrinogen or its purified fractions FI, FII and FIII-IV-V were added to washed platelets in the presence of Tyrode-HEPES buffer pH 7.4. Aggregation was initiated by the addition of calcium and ADP. These fibrinogen fractions equally promoted ADP-induced platelet aggregation. The major difference among these fractions is in their Aα chains. The FI fraction contains intact Aα chains while FII and FIH-IV-V fractions have one and two partially degraded Aα chains at the carboxy terminal portion respectively. We conclude that the carboxy terminal portion of the Aα chain does not play an important role in promoting ADP-induced platelet aggregation.

Synthesis and biological properties of cholecystokinin heptapeptide analogues containing D- and L-forms of tert-leucine or neopentylglycine in position 5

1991 ◽  
Vol 56 (10) ◽  
pp. 2209-2217 ◽  
Author(s):  
Jan Hlaváček ◽  
Jana Pírková ◽  
Jan Pospíšek ◽  
Jiřina Slaninová ◽  
Lenka Maletínská
Keyword(s):  
Gall Bladder ◽  
Solid Phase ◽  
Biological Activities ◽  
Biological Properties ◽  
Phase Synthesis ◽  
Structural Modifications ◽  
Bladder Contraction ◽  
Anorectic Effect ◽  
Carboxy Terminal ◽  
Anorectic Activity

Using solution or solid-phase synthesis we prepared the cholecystokinin fragment Boc-CCK-7 (Boc-Tyr-(SO3-.Na+)-Met-Gly-Trp-Met-Asp-PheNH2) and its four analogues in which the methionine moiety (Met) in the carboxy-terminal part is replaced by tert-leucine (Tle) or neopentylglycine (Neo) residue or D-enantiomers of these non-coded amino acids. These structural modifications led to reduction of the studied biological activities (gall bladder contraction, anorectic activity, analgetic and sedation activity) of all prepared analogues except Boc[Neo5]-CCK-7 which, being less analgetically active, retains full gall bladder and sedation activity of CCK-8. Moreover, its anorectic activity is substantially higher (400%). This analogue is very interesting particularly for its selectively increased (4x) anorectic effect compared with that of CCK-8.

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