Models for protein-zinc ion binding sites. II. The catalytic sites

2001 ◽  
Vol 83 (3-4) ◽  
pp. 150-165 ◽  
Author(s):  
David W. Deerfield ◽  
Charles W. Carter ◽  
Lee G. Pedersen
2018 ◽  
Vol 116 (2) ◽  
pp. 528-533 ◽  
Author(s):  
Ivan B. Lomakin ◽  
Sergey E. Dmitriev ◽  
Thomas A. Steitz

The density-regulated protein (DENR) and the malignant T cell-amplified sequence 1 (MCT-1/MCTS1) oncoprotein support noncanonical translation initiation, promote translation reinitiation on a specific set of mRNAs with short upstream reading frames, and regulate ribosome recycling. DENR and MCT-1 form a heterodimer, which binds to the ribosome. We determined the crystal structure of the heterodimer formed by human MCT-1 and the N-terminal domain of DENR at 2.0-Å resolution. The structure of the heterodimer reveals atomic details of the mechanism of DENR and MCT-1 interaction. Four conserved cysteine residues of DENR (C34, C37, C44, C53) form a classical tetrahedral zinc ion-binding site, which preserves the structure of the DENR’s MCT-1–binding interface that is essential for the dimerization. Substitution of all four cysteines by alanine abolished a heterodimer formation. Our findings elucidate further the mechanism of regulation of DENR-MCT-1 activities in unconventional translation initiation, reinitiation, and recycling.


1991 ◽  
Vol 23 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Masato Nanasawa ◽  
Takahiro Nishiyama ◽  
Hiroyoshi Kamogawa

1981 ◽  
Author(s):  
R M Lewis ◽  
H M Reisner ◽  
B C Abels ◽  
H R Roberts

Affinity chromatography of an inhibitor to human factor IX (F.IX) separated the antibody into two populations. The ion dependent population of antibodies had an absolute divalent cation (Me++) binding requirement. The non-ion dependent population bound F.IX equally in the presence or absence of Me++. The concentration of Me++ required for ½ the maximum ion dependent antibody binding (½ max) was (in nM) Ca++ 0.40, Mn++ 0.05, Sr++ 0.70 and Mg++ 0.65.Ca++ potentiated the binding of antibody in the presence of excess Mg++. In addition, the ½ max for Ca++ was reduced about four fold. These observations are consistent with separate binding sites on the F.IX molecule for Ca++ and Mg++ and potentiation of Ca++ binding by Mg++. Scat- chard analysis of ion dependent antibody binding indicates about a 10 fold greater affinity of antibody in the presence of Ca++ than Mg++. In the presence of both cations, affinity was at least as high as in the presence of Ca++ alone supporting the presence of separate ion binding sites on the F.IX molecule.


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