Members of this family are related to cytosylglucuronate (CGA) synthase (), and found in the same clusters as CGA synthase and CGA decarboxylase. These clusters produce peptidyl nucleoside antibiotics with a pyranoside core moiety, found in a number of Streptomyces species. Removal of the S. griseochromogenes member of this family, BlsF, from a heterologous expression system caused an increase, not blockage, of blasticidin S [].
BlsE, part of the blasticidin S biosynthetic pathway, is a radical SAM enzyme that performs a decarboxylation at C5 of the glucoside residue. MilG in mildiomycin biosynthesis is equivalent. This enzyme follows CGA synthase and makes the pyranoside core moiety of a class of peptidyl nucleoside antibiotics [].
Secretogranin-3 is a family of vertebrate proteins that is one of the granin family. Granins are rich in acidic amino acids, exhibit aggregation at low pH, and possess a high capacity for calcium binding. Because granins are restricted in their localisation to secretory granules of neuroendocrine cells, two interesting characteristics of their sorting mechanisms have been observed. These are, first, that they aggregate on low pH/high calcium concentrations and second that two of them carry an N-terminal disulfide loop, mutations in which lead to mis-sorting. Thus, granins are thought to be essential for the sorting of secretory proteins at the trans-Golgi network. Chromogranin A (CgA) binds to SGIII in secretory granules of endocrine cells []. SGIII directly binds to cholesterol components of the secretory granule membrane and targets CgA to secretory granules in pituitary and pancreatic endocrine cells []. Mutations in the SGIII gene may influence the risk of obesity through possible regulation of hypothalamic neuropeptide secretion [].Secretogranin-3 interacts with cromogranin A; this interaction is optimal in conditions mimicking the lumenal milieu of the trans-Golgi network, i.e. pH 5.5 and 10 mM Ca(+2) [].
Granins (chromogranins or secretogranins) []are a family of acidic proteins present in the secretory granules of a wide variety of endocrine and neuro-endocrine cells. The exact function(s) of these proteins is not yet known but they seem to be the precursors of biologically active peptides and/or they may act as helper proteins in the packaging of peptide hormones and neuropeptides. Apart from their subcellular location and the abundance of acidic residues (Asp and Glu), these proteins do not share many structural similarities. Only one short region, located in the C-terminal section, is conserved in all these proteins, such as:Chromogranin A (CGA): CGA is a protein of about 420 residues; it is the precursor of the peptide pancreastatin which strongly inhibits glucose- induced insulin release from the pancreas.Secretogranin 1 (chromogranin B): A sulfated protein of about 600 residues.Secretogranin 2 (chromogranin C): A sulfated protein of about 650 residues.Chromogranins and secretogranins together share a C-terminal motif, whereas chromogranins A and B share a region of high similarity in their N-terminal section; this region includes two cysteine residues involved in a disulphide bond.
Granins (chromogranins or secretogranins) []are a family of acidic proteins present in the secretory granules of a wide variety of endocrine and neuro-endocrine cells. The exact function(s) of these proteins is not yet known but they seem to be the precursors of biologically active peptides and/or they may act as helper proteins in the packaging of peptide hormones and neuropeptides. Apart from their subcellular location and the abundance of acidic residues (Asp and Glu), these proteins do not share many structural similarities. Only one short region, located in the C-terminal section, is conserved in all these proteins, such as:Chromogranin A (CGA): CGA is a protein of about 420 residues; it is the precursor of the peptide pancreastatin which strongly inhibits glucose- induced insulin release from the pancreas.Secretogranin 1 (chromogranin B): A sulfated protein of about 600 residues.Secretogranin 2 (chromogranin C): A sulfated protein of about 650 residues.Chromogranins and secretogranins together share a C-terminal motif, whereas chromogranins A and B share a region of high similarity in their N-terminal section; this region includes two cysteine residues involved in a disulphide bond.
