Polypeptide sequence

For a polypeptide chain of 100 residues in length, a rather modest size, the number of possible sequences is 20 , or because 20 = lO, lO unique possibilities. These numbers are more than astronomical Because an average protein molecule of 100 residues would have a mass of 13,800 daltons (average molecular mass of an amino acid residue = 138), lO such molecules would have amass of 1.38 X lO " daltons. The mass of the observable universe is estimated to be 10 proton masses (about 10 daltons). Thus, the universe lacks enough material to make just one molecule of each possible polypeptide sequence for a protein only 100 residues in length. 

Messenger RNA (mRNA) serves to carry the information or message that is encoded in genes to the sites of protein synthesis in the cell, where this information is translated into a polypeptide sequence. Because mRNA molecules are transcribed copies of the protein-coding genetic units that comprise most of DNA, mRNA is said to be the DNA-like RNA. ... 

HSFl phosphorylation must be sensitive to nonheat inducers of HSF-DNA binding activity because HSFl phosphorylation can be achieved at 37 °C by other inducers of the HS response. HSF 1 contains polypeptide sequences that could serve as substrates for well characterized protein kinases, but few of these are known to be heat inducible. One family of protein kinases, the S6 protein kinases, have already been shown to exhibit heat inducible activity however, their peak level of activity during HS occurs well after the maximal induction of HSF phosphorylation (Jurivich et al., 1991). Thus, other protein kinases are likely to be directly linked to the phosphorylation of HSF. Some of the putative protein phosphorylation sites on HSF include motifs for protein kinase C, casein kinase, and enterokinase. There are tyrosine sequences that match substrates for known tyrosine kinases, but whether these residues are accessible to phosphorylation is not established. 

Elizabeth et al. [108] reported an elastin-mimic polypeptide sequence that mimics triblock copolymers (ABA) with the sequence of the respective blocks as... 

Before discussing the ROA band signatures and general spectral characteristics of the disordered types of structure found in unfolded proteins, it is helpful to review the ROA band signatures of cc-helix and /1-sheet together with those of loops, turns, and side chains, as shown by folded proteins containing significant amounts of extended secondary structure in order to demonstrate that ROA is able to discriminate adequately between ordered and disordered polypeptide sequences. Typical... 

Studies have actually revealed two type I interferon receptor polypeptides. Sequence data from cloning studies place both in the class II cytokine receptor family. Both are transmembrane N-linked glycoproteins. Studies using isolated forms of each show that one polypeptide (called the a/p receptor) is capable of binding all type I interferons. The other one (the ap receptor) is specific for IFN-a-B (a specific member of the IFN-a family). Both receptors are present on most cell types. 

GH induces its characteristic biological effects by binding to a specific cell surface receptor. The human receptor is a single-chain 620 amino acid transmembrane polypeptide. Sequence analysis... 

X. Kong and S.A. Jenekhe, Block copolymers containing conjugated polymer and polypeptide sequences synthesis and self-assembly of electroactive and photoactive nanostructures, Macromolecules, 37 8180-8183, 2004. 

Although varying considerably in molecular size, any GPCR polypeptide sequence contains seven hydrophobic a-helices that span the lipid bilayer and dictate the typical macromolecule architecture. Seven transmembrane domains bundled up to form a polar internal tunnel and expose the N-terminus and three interconnecting loops, to the exterior, and the C-terminus with a matching number of loops, to the interior of the cell [1-3]. This structural information was recently confirmed by the resolution of the crystal structure of rhodopsin [4,5]. 

Within the light and heavy chains are domains, which consist of about 110 amino acids. The domains that have similar polypeptide sequence are termed constant domains.These are the ChI, Ch2, and Ch3 domains of the heavy chain... 

In fact, the cross-talk between histone methylation and DNA methylation has been experimentally demonstrated for the first time in Neurospora [145] (see commentary by Bird [146]) and proved the second scenario. Using the power of Neurospora genetics, Tamaru and Selker [145] have identified a gene which, when mutated, abolishes methylation of all tested DNA sequences. This gene, dim-5, is different from dim-2, the previously identified gene that encodes the only DNA methyltransferase in Neurospora responsible for all known cytosine methylation in this fungus. The dim-5 gene encodes a histone H3 methyltransferase the deduced polypeptide sequence contains a SET domain with sequence similarity to some known histone methyltransferases moreover, the recombinant DIM-5 protein exhibits histone methyltransferase activity in vitro. Additional in vivo experiments... 

One strategy to control folding is to direct folds by introduction of S-hairpins, turns which are often associated with Pro incorporation in a polypeptide sequence. Constrained turn mimics have previously been employed in investigations of the active conformation of peptides. Clearly, from the above discussion of CyP and... 

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