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Signal transduction and exercise
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Brendan Egan, Adam P. Sharples
While all three processes are tightly regulated, the rate-limiting step for translational control occurs at the initiation step. Translation initiation is a multi-step process regulated by eukaryotic initiation factors (eIFs) and culminates in formation of the 80S initiation complex. Prior to translation, the subunits of the ribosome are separate and the 40S subunit must be ‘primed’ by binding of a transfer RNA (tRNA). The tRNA contains the complementary sequence for the AUG start codon of mRNA and is also attached to the amino acid methionine. Proteins are synthesised beginning from the amine N-terminal and ending with a carboxyl C-terminal; therefore, all proteins begin with a methionine residue, although this is often removed after translation. The priming of the 40S ribosome is regulated in part by eIF3 and creates a 43S pre-initiation complex. Next eIF4 guides the 5’-end (named 5’-cap) of mRNA into the 43S complex and the ribosome proceeds along the mRNA until the start codon is found. Other eIFs then recruit the 60S subunit to create the 80S initiation complex, and synthesis of the polypeptide chain begins.
Macronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
In cells, a peptide is formed when two adjacent amino acids are linked together through the carboxyl (COOH) group of one amino acid with the amino (NH2) group of another to form an amide bond (-CONH-), also called peptide bond. The chain, thus formed, by linking together of many amino acid units is called a peptide chain (36, 38, 41). The two amino acids at the ends of the chain are called N-terminal and C-terminal where the groups NH2 and COOH are not linked – free or intact. Depending on the number of amino acid molecules composing a chain, the peptides may be termed as a dipeptide (containing 2 amino acid units), a tripeptide (containing 3 amino acid units) and so on. If a peptide is made up of no more than ten amino acids, it is called an oligopeptide; beyond that, it is a polypeptide. Peptide chain may possess from 50 to millions of amino acid units. When they are made up of over 100 amino acids, polypepties are sometimes called macro-peptides. Strictly speaking, proteins are polypeptides with more than 100 amino acids (38). However, this classification is arbitrary, and the number of amino acids can vary according to each author.
What Are Polymeric Carriers?
Published in Mesut Karahan, Synthetic Peptide Vaccine Models, 2021
Gülderen Karakuş, Dolunay Şakar Daşdan
Depending on the peptide sequence, as in the conjugation region proteins, the N-terminus of the sequence may be the C-terminus or a point within it. The conjugation point may be carboxyl (-COOH), amino (-NH2), or sulfhydryl (-SH) ends. Synthetic peptides, haptens, etc., when used as a vaccine, have a significant effect. Nowadays, it is widely used to create specific antibodies. However, therapeutic agents and synthetic peptides or haptens, due to their low solubility, instability, low molecular weight, low antigenic properties, undesirable properties such as biocompatibility, and non-specificity or cytokine toxicity have greatly reduced their ability to act. However, the formation of conjugates of proteins, antigens, or actives with water-soluble polymers significantly changes the properties and immunogenicity of the therapeutic agents.
VERITAS: Harnessing the power of nomenclature in biologic discovery
Published in mAbs, 2023
Riti Biswas, Ed Belouski, Kevin Graham, Michelle Hortter, Marissa Mock, Christine E. Tinberg, Alan J. Russell
The following example illustrates the VERITAS scheme and its ability to describe structure. Consider the molecule format called [Fab*scFv]-heteroFc in the 1 + 1 section of Figure 1. When the heteroFc is designated as the central focus, i.e., “multimerization center”, of the molecule, the Fab and scFv are both attached to the N-terminus of the center. Amino acid sequences are read N-terminus to C-terminus and are therefore written left to right. Thus, it is logical to place “Fab” and “scFv” to the left of “heteroFc”. Now, how can we relay the relationship between the Fab and the scFv? These modules are attached to two separate chains of the heteroFc, so let us use an asterisk (“*”) between them. “Fab*scFv”, which is the description of the N-terminal appendages to the “heteroFc” center, is enclosed in square brackets (“[]”) for readability and to quickly indicate that this molecule format is asymmetric.
Combining human platelet proteomes and transcriptomes: possibilities and challenges
Published in Platelets, 2023
Jingnan Huang, Johan W.M. Heemskerk, Frauke Swieringa
The workflow for bottom-up proteomic analyses (i.e., without gel separation) encompasses sample preparation of protein lysates via either trichloroacetic acid and/or acetone protein precipitation, combined with in-solution trypsin digestion.25 Some papers use a filter-aided sample preparation (FASP) before trypsin digestion. Such bottom-up analyses give a high number of identified proteins, although the use of trypsin is seen as a limitation, since this protease can cleave in an imprecise way and may over- or under-digest specific peptide sequences. If required, additional sample treatment steps can include an enrichment for phosphorylated peptides, which for instance is performed by metal oxide affinity chromatography using titanium dioxide (TiO2) beads, in combination with hydrophilic interaction liquid chromatography (HILIC).26 In addition, digested protein samples can be prepared for the assessment of N-terminal cleavage, ubiquitinoylation, acetylation or glycopeptide sites.3 The comparison of samples is possible by stable isotope labeling, for instance using isobaric tags for relative and absolute quantification (iTRAQ) or using tandem mass tags (TMT).27
The role of N-myristoyltransferase 1 in tumour development
Published in Annals of Medicine, 2023
Hong Wang, Xin Xu, Jiayi Wang, Yongxia Qiao
Myristoylation plays a role in signal transduction, immune regulation and tumour development [7,20–23]. The process of myristoylation relies on a key enzyme, N-myristoyltransferase (NMT). During myristoylation, myristoyl coenzyme A binds to NMT and then the peptide substrate, and finally myristoyl coenzyme A is transferred to the N-terminal glycine residue of the substrate and NMT releases coenzyme A molecules and myristoylated proteins [8,10]. NMT is an indispensable enzyme for the growth and development of many eukaryotes and viruses [18,24–27] and is usually present in vivo as an isoenzyme [21]. Two major isoforms, N-myristoyltransferase 1 (NMT1) and N-myristoyltransferase 2 (NMT2), exist in higher eukaryotes and they share approximately 77% amino acid sequence similarity [28]. In humans, NMT2 exists as a single 65 kDa protein, while NMT1 exists as four different isoforms ranging in size from 49 to 68 kDa [28].