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Saposin Protein Domain
The saposin domains refers to two evolutionally-conserved protein domains found in saposin and related proteins (SAPLIP). Saposins are small lysosomal proteins that serve as activators of various lysosomal lipid-degrading enzymes. They probably act by isolating the lipid substrate from the membrane surroundings, thus making it more accessible to the soluble degradative enzymes. All mammalian saposins are synthesized as a single precursor molecule ( prosaposin) which contains four ''Saposin-B domains'', yielding the active saposins after proteolytic cleavage, and two ''Saposin-A domains'' that are removed in the activation reaction. The Saposin-B domains also occur in other proteins, most of them playing a role in interacting with membranes. Classification The saposin (SapB1-SapB2) domains are found in a wide range of proteins. Each half-domain encodes two alpha helices in the SapB domain for a total of four. The mamallian prosaposin (domain organization below) is a prototypi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Domain
In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of several domains, and a domain may appear in a variety of different proteins. Molecular evolution uses domains as building blocks and these may be recombined in different arrangements to create proteins with different functions. In general, domains vary in length from between about 50 amino acids up to 250 amino acids in length. The shortest domains, such as zinc fingers, are stabilized by metal ions or disulfide bridges. Domains often form functional units, such as the calcium-binding EF hand domain of calmodulin. Because they are independently stable, domains can be "swapped" by genetic engineering between one protein and another to make chimeric proteins. Background The concept of the domain was first proposed in 1973 by Wetlaufer af ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circular Permutation In Proteins
A circular permutation is a relationship between proteins whereby the proteins have a changed order of amino acids in their peptide sequence. The result is a protein structure with different connectivity, but overall similar three-dimensional (3D) shape. In 1979, the first pair of circularly permuted proteins – concanavalin A and lectin – were discovered; over 2000 such proteins are now known. Circular permutation can occur as the result of evolutionary events, posttranslational modifications, or artificially engineered mutations. The two main models proposed to explain the evolution of circularly permuted proteins are ''permutation by duplication'' and ''fission and fusion''. Permutation by duplication occurs when a gene undergoes duplication to form a tandem repeat, before redundant sections of the protein are removed; this relationship is found between saposin and swaposin. Fission and fusion occurs when partial proteins fuse to form a single polypeptide, such as in nic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Domains
In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of several domains, and a domain may appear in a variety of different proteins. Molecular evolution uses domains as building blocks and these may be recombined in different arrangements to create proteins with different functions. In general, domains vary in length from between about 50 amino acids up to 250 amino acids in length. The shortest domains, such as zinc fingers, are stabilized by metal ions or disulfide bridges. Domains often form functional units, such as the calcium-binding EF hand domain of calmodulin. Because they are independently stable, domains can be "swapped" by genetic engineering between one protein and another to make chimeric proteins. Background The concept of the domain was first proposed in 1973 by Wetlaufer aft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PROSITE
PROSITE is a protein database. It consists of entries describing the protein families, domains and functional sites as well as amino acid patterns and profiles in them. These are manually curated by a team of the Swiss Institute of Bioinformatics and tightly integrated into Swiss-Prot protein annotation. PROSITE was created in 1988 by Amos Bairoch, who directed the group for more than 20 years. Since July 2018, the director of PROSITE and Swiss-Prot is Alan Bridge. PROSITE's uses include identifying possible functions of newly discovered proteins and analysis of known proteins for previously undetermined activity. Properties from well-studied genes can be propagated to biologically related organisms, and for different or poorly known genes biochemical functions can be predicted from similarities. PROSITE offers tools for protein sequence analysis and motif detection (see sequence motif, PROSITE patterns). It is part of the ExPASy proteomics analysis servers. The database ProR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SFTPB
Surfactant protein B is an essential lipid-associated protein found in pulmonary surfactant. Without it, the lung would not be able to inflate after a deep breath out. It rearranges lipid molecules in the fluid lining the lung so that tiny air sacs in the lung, called alveoli, can more easily inflate. Gene SP-B is encoded by ''SFTPB'', a single, 11425 nucleotide long gene on chromosome 2. Mutations in this gene are the basis for several of the lung conditions mentioned above. Both frameshift mutations and several single nucleotide polymorphisms (SNPs) have been found correlated to a variety of lung conditions. A frame shift mutation responsible for congenital alveolar proteinosis (CAP) was identified by Kattan et al. Many SNP's have been identified in relation to lung conditions. They have been correlated to severe influenza, neonatal respiratory distress syndrome, mechanical ventilation necessity, and more. Protein Surfactant protein B (SP-B) is a small protein, weighi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PSAPL1
Proactivator polypeptide-like 1 is a protein in humans that is encoded by the PSAPL1 gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b .... It is a member of the saposin family of proteins. References Further reading Genes on human chromosome 4 Pseudogenes {{gene-4-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prosaposin
Prosaposin, also known as PSAP, is a protein which in humans is encoded by the ''PSAP'' gene. This highly conserved glycoprotein is a precursor for 4 cleavage products: saposins A, B, C, and D. Saposin is an acronym for Sphingolipid Activator PrO ''SeINs. Each domain of the precursor protein is approximately 80 amino acid residues long with nearly identical placement of cysteine residues and glycosylation sites. Saposins A-D localize primarily to the lysosomal compartment where they facilitate the catabolism of glycosphingolipids with short oligosaccharide groups. The precursor protein exists both as a secretory protein and as an integral membrane protein and has neurotrophic activities. Saposins A–D are required for the hydrolysis of certain sphingolipids by specific lysosomal hydrolases. Family members * Saposin A was identified as an N-terminal domain in the prosaposin cDNA prior to its isolation. It is known to stimulate the enzymatic hydrolysis of 4-methylumbelliferyl-Π... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GNLY
Granulysin (GNLY) is a protein expressed in most mammals which functions as an antimicrobial peptide Antimicrobial peptides (AMPs), also called host defence peptides (HDPs) are part of the innate immune response found among all classes of life. Fundamental differences exist between prokaryotic and eukaryotic cells that may represent targets for a ... released by killer lymphocytes in cytotoxic granules. It is a pore-forming peptide, as it can puncture a microbial cell wall, allowing for other death-inducing enzymes to enter the microbe and cause microptosis. GNLY is inhibited by cholesterol, and is most effective in helping to kill cholesterol-deficient microbes. It is part of the saponin-like protein family, and its gene is found on the 2nd chromosome in humans. It is distinguished by its 5 α-helical structure. Its expression is restricted to cytotoxic immune cells such as cytotoxic T cells, Natural killer cell, NK cells, Natural killer T cell, NKT cells and Gamma delta T cell, Π... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AOAH
Acyloxyacyl hydrolase, also known as AOAH, is a protein which in humans is encoded by the ''AOAH'' gene. Function Acyloxyacyl hydrolase (AOAH) is a lipase that selectively releases the secondary (acyloxyacyl-linked) fatty acyl chains from the hexaacyl lipid A moiety found in many bacterial lipopolysaccharide Lipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide that are bacterial toxins. They are composed of an O-antigen, an outer core, and an inner core all joined by a covalent bond, and are found in the outer ...s (LPSs, also called endotoxins). The resulting tetraacyl LPS is non-stimulatory and can be a potent inhibitor of LPS sensing via the MD-2--Toll-like Receptor 4 (TLR4). The enzyme's 2 disulfide-linked subunits are encoded by a single mRNA. The smaller subunit is a member of the saposin-like (SAPLIP) protein family and the larger subunit, which contains the active site serine, is a GDSL lipase. The enzyme's 3D structure and c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant-specific Insert
The plant-specific insert (PSI) or plant-specific sequence (PSS) is an independent domain, exclusively found in plants, consisting of approximately 100 residues, found on the C-terminal lobe on some aspartic proteases (AP) called phytepsins. The PSI, as an independent entity separate from its parent AP, is homologous to saposin and belongs to the saposin-like protein family (SAPLIP). Although the PSI is grouped along proteins in the SAPLIP family, the PSI does not contain a proper saposin-like domain. This is due to a circular permutation of the N- and C-termini of the PSI, in which the termini are "swapped". This has led to the PSI being termed a "swaposin" (a play-on-words of "swap" and "saposin") although the tertiary structure still remains homologous to saposin and other members of the SAPLIP family. Structure Among plants, APs between different species are generally homologous exhibiting high sequence identity whilst maintaining a similar tertiary structure to pepsin. As ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saposin
Prosaposin, also known as PSAP, is a protein which in humans is encoded by the ''PSAP'' gene. This highly conserved glycoprotein is a precursor for 4 cleavage products: saposins A, B, C, and D. Saposin is an acronym for Sphingolipid Activator PrO ''SeINs. Each domain of the precursor protein is approximately 80 amino acid residues long with nearly identical placement of cysteine residues and glycosylation sites. Saposins A-D localize primarily to the lysosomal compartment where they facilitate the catabolism of glycosphingolipids with short oligosaccharide groups. The precursor protein exists both as a secretory protein and as an integral membrane protein and has neurotrophic activities. Saposins A–D are required for the hydrolysis of certain sphingolipids by specific lysosomal hydrolases. Family members * Saposin A was identified as an N-terminal domain in the prosaposin cDNA prior to its isolation. It is known to stimulate the enzymatic hydrolysis of 4-methylumbelliferyl-Π... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prosaposin Schematic
Prosaposin, also known as PSAP, is a protein which in humans is encoded by the ''PSAP'' gene. This highly conserved glycoprotein is a precursor for 4 cleavage products: saposins A, B, C, and D. Saposin is an acronym for Sphingolipid Activator PrO ''SeINs. Each domain of the precursor protein is approximately 80 amino acid residues long with nearly identical placement of cysteine residues and glycosylation sites. Saposins A-D localize primarily to the lysosomal compartment where they facilitate the catabolism of glycosphingolipids with short oligosaccharide groups. The precursor protein exists both as a secretory protein and as an integral membrane protein and has neurotrophic activities. Saposins A–D are required for the hydrolysis of certain sphingolipids by specific lysosomal hydrolases. Family members * Saposin A was identified as an N-terminal domain in the prosaposin cDNA prior to its isolation. It is known to stimulate the enzymatic hydrolysis of 4-methylumbelliferyl-Π... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
