A review of protein structure and gene organisation for proteins associated with mineralised tissue and calcium phosphate stabilisation encoded on human chromosome 4

Identification and characterization of integrin-binding sialoprotein (IBSP) genes in reptile and amphibian

“…One category of NCPs has been termed as the small integrin-binding ligand N -linked glycoprotein (SIBLING) family, based on their common characteristics (Fisher et al, 2001). This family originally consisted of integrin-binding sialoprotein (IBSP, bone sialoprotein), secreted phosphoprotein 1 (SPP1, osteopontin), dentin matrix protein 1 (DMP1), dentin sialophosphoprotein (DSPP), and matrix extracellular phosphoglycoprotein (MEPE), which have been shown to be closely linked on human, mouse, rat (Huq et al, 2005), and chicken (Kawasaki and Weiss, 2006) chromosomes. Thus, it is considered that this entire family might be the result of duplication and subsequent divergent evolution of a single ancient gene (Fisher et al, 2001), and may be cruc ial to the evolution of vertebrate tissue mineralization (Kawasaki and Weiss, 2006).…”

Immunocytochemistry of matrix proteins in calcified tissues: functional biochemistry on section

“…Collectively, these stabilizing proteins are referred to as the secretory calcium-binding phosphoprotein gene cluster. All of them, with the exception of AMEL, are located on human chromosome 4q (14 in rat and 5 in mouse) (Huq et al 2005). It has been proposed that these proteins derive from the duplication and diversification of an ancestral gene during evolution, that is from the 5' region of SPARC-like-1 which initially arose from osteonectin/SPARC duplication about 600 million years ago (Huq et al 2005;Sire et al 2005).…”

“…Formative cells achieve this by creating microenvironments which facilitate mineral ion handling and by secreting proteins that stabilize Ca and PO4 ions in body fluids and/or control their deposition onto a receptive extracellular matrix (ECM). Genome sequencing and gene mapping have shown that several of these proteins are located on the same chromosome and that there is synteny across several species (Huq et al 2005). In mammals, these stabilizing proteins include (i) ameloblastin (AMBN), amelogenin (AMEL) and enamelin in enamel; (ii) bone sialoprotein (BSP), dentin sialophosphoprotein, dentin matrix acidic phosphoprotein-1, matrix extracellular phosphoglycoprotein and osteopontin (OPN) in bone, dentin and to some extent in cementum, (iii) statherin, histatin and proline-rich proteins in saliva, and (iv) caseins in milk.…”

“…All of them, with the exception of AMEL, are located on human chromosome 4q (14 in rat and 5 in mouse) (Huq et al 2005). It has been proposed that these proteins derive from the duplication and diversification of an ancestral gene during evolution, that is from the 5' region of SPARC-like-1 which initially arose from osteonectin/SPARC duplication about 600 million years ago (Huq et al 2005;Sire et al 2005). Recently, two novel proteins produced by ameloblasts, APIN and Amelotin, have been identified and their genes are also located to the secretory calcium-binding phosphoprotein cluster.…”

“…Essentially, once CaPO4 deposition is initiated, the crux is then to control the spontaneous precipitation of mineral ions from supersaturated tissue fluids and limit it to well-defined sites (Huq et al 2005;Murshed et al 2005;Wilt 2005). Formative cells achieve this by creating microenvironments which facilitate mineral ion handling and by secreting proteins that stabilize Ca and PO4 ions in body fluids and/or control their deposition onto a receptive extracellular matrix (ECM).…”