Sequence similarities serve as evidence for structural and functional conservation, as well as of evolutionary relationships between the sequences. Consequently, comparative analysis is the primary means by which functional elements are identified.
Among the most highly conserved sequences are the active sites of enzymes and the binding sites of a protein receptors.
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In biology, conserved sequences are similar or identical sequences that may occur within nucleic acids, proteins or polymeric carbohydrates within multiple species of organism or within different molecules produced by the same organism. In the case of cross species conservation, this indicates that a particular sequence may have been maintained by evolution despite speciation. The further back up the phylogenetic tree a particular conserved sequence may occur the more highly conserved it is said to be.
Endogenous retroviral sequence 3 (includes zinc finger protein H-plk/HPF9), also known as ERV3, is a human gene.[1] The human genome includes many retroelements including the human endogenous retroviruses (HERVs). ERV3, one of the most studied HERVs, is thought to have integrated 30 to 40 million years ago and is present in higher primates with the exception of gorillas. Taken together, the observation of genome conservation, the detection of transcript expression, and the presence of conserved ORFs is circumstantial evidence for a functional role. A functional role is also suggested by the observation that downregulation of ERV3 is reported in choriocarcinoma.[1]
Alloenzymes are common biological enzymes that exhibit high levels of functional evolutionary conservation throughout specific phylas and kingdoms. They are used by phylogeneticists as molecular markers to gauge evolutionary histories and relationships between different species of organisms. These enzymes generally perform very basic functions found commonly throughout all lifeforms, such as DNA polymerase, the enzyme that repairs and copies DNA. Significant changes in this enzyme reflect significant events in evolutionary history of organisms. As expected DNA polymerase shows relatively small differences in its amino acid sequence between phyla and even kingdoms. The key to choosing which alloenzyme to use in a comparison
Heat shock proteins are amongst the most evolutionarily conserved of proteins.[6] The significant function, structural, and sequential homology between HSP60 and its prokaryotic homolog, groEL, demonstrates this level of conservation. Moreover, HSP60’s amino acid sequence bears a similarity to its homolog in plants, bacteria, and humans.[1] Heat shock proteins are primarily responsible for maintaining the integrity of cellular proteins particularly in response to environmental changes. Stresses such a temperature, concentration imbalance, pH change, and toxins can all induce heat shock proteins to maintain the conformation of the cell’s proteins. HSP60 constitutes approximately 15-30% of all cellular proteins.[7] In additional to
In addition to the bovine and porcine tissue from which pharmaceutical-grade heparin is commonly extracted, heparin has also been extracted and characterised from the following species: Turkey.[33] Whale.[34] Dromedary camel.[35] Mouse.[36] Humans.[37] Lobster.[38] Fresh water mussel.[39] Clam.[40] Shrimp.[41] Mangrove crab.[42] Sand dollar.[42] The biological activity of heparin within species 6–11 is unclear and further supports the idea that the main physiological role of heparin is not anticoagulation. These species do not possess any blood coagulation system similar to that present within the species listed 1–5. The above list also demonstrates how heparin has been highly evolutionarily conserved with molecules of a similar structure being produced by a broad range of organisms belonging
Typical stages in a U6 snRNA (also termed class III) gene initiation (documented in vertebrates only): SNAPc (SNRNA Activating Protein complex) (also termed PBP and PTF) binds to the PSE (Proximal Sequence Element) centered approximately 55 base pairs upstream of the start site of transcription. This assembly is greatly stimulated by the Pol II transcription factors Oct1 and STAF that bind to an enhancer-like DSE (Distal Sequence Element) at least 200 base pairs upstream of the start site of transcription. These factors and promoter elements are shared between Pol II and Pol III transcription of snRNA genes. SNAPc acts to assemble TFIIIB
The first protein in the FOX family that was discovered was the fork head transcription factor in Drosophila (thus the name). Since then a large number of family members have been discovered, especially in vertebrates. Originally they were given vastly different names (such as HFH, FREAC, and fkh), but in 2000 a unified nomenclature was introduced that grouped the FOX proteins into subclasses (FOXA-FOXS) based on sequence conservation.[5]
The Biological Value method is also used for analysis in animals such as cattle, poultry, and various laboratory animals such as rats. It was used by the poultry industry to determine which mixtures of feed were utilized most efficiently by developing chicken. Although the process remains the same, the biological values of particular proteins in humans differs from their biological values in animals due to physiological variations.[
A biological target is a biopolymer such as a protein or nucleic acid whose activity can be modified by an external stimulus. The definition is context-dependent and can refer to the biological target of a pharmacologically active drug compound, or the receptor target of a hormone (like insulin). The implication is that a molecule is "hit" by a signal and its behavior is thereby changed. Biological targets are most commonly proteins such as enzymes, ion channels, and receptors.
Human RLI was first identified because of its ability to inhibit RNAse L, which plays a crucial role in antiviral activity in mammals. This cannot account for the conservation of the protein in all other organisms, since only mammals have the RNAse L system. It has been suggested that RLI in lower eukaryotes functions by inhibiting RNAses involved in ribosomal biosynthesis, thereby regulating the process. [3]
A PEST sequence is a peptide sequence which is rich in proline (P), glutamic acid (E), serine (S), and threonine (T). This sequence is associated with proteins that have a short intracellular half-life; hence, it is hypothesized that the PEST sequence acts as a signal peptide for protein degradation.[1] The degradation may be mediated possibly via the proteosome[2][3] or calpain[4].
POU domain genes have been described in organisms as divergent as Caenorhabditis elegans, Drosophila, Xenopus, zebrafish and human but have not been yet identified in plants and fungi. D'Souza et al (PNAS, 91:9397-9401. 1994) demonstrated a surprisingly high degree of amino acid sequence conservation (37%-42%) of POU homeodomains to the transcriptional regulator comS from the gram positive prokaryote Bacillus subtilis. Interestingly, akin to the way that POU homeodomain regulators lead to tissue differentiation in metazoans, this transcription factor is critical for differentation of a subpopulation of B. subtilis into a state of genetic competence.
Serum amyloid A (SAA) proteins are a family of apolipoproteins associated with high-density lipoprotein (HDL) in plasma. Different isoforms of SAA are expressed constitutively (constitutive SAAs) at different levels or in response to inflammatory stimuli (acute phase SAAs). These proteins are predominantly produced by the liver.[1] The conservation of these proteins throughout invertebrates and vertebrates suggests SAAs play a highly essential role in all animals.[2]
"Any process that modulates the frequency, rate or extent of a biological process. Biological processes are regulated by many means; examples include the control of gene expression, protein modification or interaction with a protein or substrate molecule."
Bone sialoprotein (BSP) is a component of mineralized tissues such as bone, dentin, cementum and calcified cartilage. BSP is a significant component of the bone extracellular matrix and has been suggested to constitute approximately 8% of all non-collagenous proteins found in bone and cementum [1]. BSP was originally isolated from bovine cortical bone as a 23-kDa glycopeptide with high sialic acid content, as described in separate reports by Williams and Peacocke [2] and Andrews and Herring [3] in 1965. Native BSP has an apparent molecular weight of 60-80 kDa based on SDS-PAGE, which is a considerable deviation from the predicted