Signature motif

The NBD unit harbors several conserved sequence motifs (Walker A and B, ABC-signature motifs), which... 

This is an emerging field that has not reached its final position yet. Members of the novel class of FCP, SCP, and HAD phosphatases require Mg2+ for catalysis. An aspartate residue within the active site signature motif (DxDx(T/V)) is essential to form an acyl-phosphate intermediate. Many members of the the HAD (haloacid dehalogenase) superfamily have phosphoesterase activity [3]. Some of those protein phosphatases act on... 

The characteristic Walker A and Walker B motifs that are involved in ATP binding [144] are always found in the ATPase or ABC domains. In addition, a signature motif, also called the LSGGQ motif, is typical of all bacterial ABC domains involved in binding-protein-dependent import. The signature motif is absent in other types of ATPases. 

Fetsch, E. E. and Davidson, A. L. (2002). Vanadate-catalyzed photocleavage of the signature motif of an ATP-binding cassette (ABC) transporter, Proc. Natl Acad. Sci. USA, 99, 9685-9690. 

F-box proteins serve as the substrate-targeting subunit of the SCF ubiquitin E3 ligase [5]. They are structurally diverse but they all contain a relatively conserved signature motif of about 45-50 amino acids [5]. This motif, the F-box, was initially... 

Figure 2. Structural and functional domains of PARP-1. PARP-1 has a highly conserved structural and functional organization including (1) an N-terminal DNA binding domain with two Cys-Cys-His-Cys zinc finger motifs (FI and Fll), (2) a nuclear localization signal (NLS), (3) a central automodification domain containing a BRCT ( BRCAl C-terminus-like ) protein-protein interaction motif, and (4) a C-terminal catalytic domain with a contiguous 50 amino acid sequence, the PARP signature motif, that forms the active site...

Hayashi Y (2000) The molecular genetics of recurring chromosome abnormalities in acute myeloid leukemia [In Process Citation]. Semin Hematol 37 368-380 Heery DM, Kalkhoven E, Hoare S, Parker MG (1997) A signature motif in transcriptional co-activators mediates binding to nuclear receptors [see comments]. Nature 387 733-736 Ida K, Kitabayashi I, Taki T, Taniwaki M, Noro K, Yamamoto M, Ohki M, Hayashi Y (1997) Adenoviral E 1 A-associated protein p300 is involved in acute myeloid leukemia with t(ll 22)(q23 ql3). Blood 90 4699-4704... 

Heery, D. M., Kalkhoven, E., Hoare, S., and Parker, M. G. (1997). A Signature Motif in Transcriptional Co-Activators Mediates Binding to Nuclear Receptors. Nature 387, 733-736. 

On the other hand, a particular protein function can be realized with different protein folds, and an example of this are protein phosphatases. Protein phosphatases feature two distinctively different catalytic mechanisms for hydrolytically cleaving phosphorylated amino acid residues. The active sites of serine/threonine protein phosphatases (PPs) contain two metal centers that directly activate a water molecule for nucleophilic attack of the phosphate ester bond. In contrast, protein tyrosine phosphatases (PTPs) [105] possess a Cys residue present in the active site loop containing the conserved PTP signature motif HCXXXXXRS. The Cys sidechain acts as the attacking nucleophile in the formation of a phosphocysteine intermediate, which is eventually hydrolyzed by a water molecule [106], The same catalytic mechanism is also shared by dual-specificity phosphatases (see below). 

Heery DM, et al. A signature motif in transcriptional co-activators mediates binding to nuclear receptors. Nature 1997 387 733-736. Glass CK, Rose DW, Rosenfeld MG. Nuclear receptor coactivators. Curr. Opin. Cell Biol. 1997 9 222-2232. 

Jumonji domain-containing, a novel demethylase signature motif... 

Figure 1. Molecular architecture and phylogenetic analysis of coronin 7 proteins. A), Domain structure of human coronin 7. Core domains consisting of WD repeats are preceded by "coronin signature" motifs. Note the low complexity proline, serine- and threonine-enriched domain preceding the second core. B), Partial comparison of amino acid sequences of human coronin 7 (top), Drosophila PODl isoform A (middle) and C. elegans POD-1 (bottom). Predicted Yxx motifs are highlighted in gray and boxed. C), Partial comparison of amino acid sequences of human, dog, mouse and rat coronin 7 (top to bottom). Predicted Yxxo motifs are highlighted in gray and boxed. See text for details.

Despite the enormous multiplicity of receptor sub-types, a limited number of basic superfamilies have been recognized that currently suffice to accommodate all of the signal transducing receptors. As an example, in the GPCRs superfamily, the signature motif of these... 

The PTPases share the signature motif (H/V)C(X)5R(S/T). This motif is also found in the low-molecular-weight PTPases, as well as in the VH 1-like dual-specific phosphatases, so-called because they dephosphorylate phosphotyrosine as well as phospho-Ser/Thr residues.129,149 These three groups of phosphatases have little sequence similarity other than the signature motif and the placement of the essential Cys and Arg residues in the active site. 

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