This family consists of several mammalian dentin matrix protein 1 (DMP1) sequences. The dentin matrix acidic phosphoprotein 1 (DMP1) gene has been mapped to human chromosome 4q21 []. DMP1 is a bone and teeth specific protein initially identified from mineralised dentin. DMP1 is primarily localised in the nuclear compartment of undifferentiated osteoblasts. In the nucleus, DMP1 acts as a transcriptional component for activation of osteoblast-specific genes like osteocalcin. During the early phase of osteoblast maturation, Ca2+surges into the nucleus from the cytoplasm, triggering the phosphorylation of DMP1 by a nuclear isoform of casein kinase II. This phosphorylated DMP1 is then exported out into the extracellular matrix, where it regulates nucleation of hydroxyapatite. DMP1 is a unique molecule that initiates osteoblast differentiation by transcription in the nucleus and orchestrates mineralised matrix formation extracellularly, at later stages of osteoblast maturation []. The DMP1 gene has been found to be ectopically expressed in lung cancer although the reason for this is unknown [].
This entry represents the fungal 20S proteasome chaperones 3 and 4 (also known as DMP1 and DMP2), which function in early 20S proteasome assembly. The structures of these chaperones have been solved, and they closely resemble that of the mammalian proteasome assembling chaperone PAC3, although there is little sequence similarity between them [].
This entry includes plant protein DMP, including Arabidopsis AtDMP1-10. DMP1 is a membrane protein that may be involved in membrane fission during breakdown of the ER and the tonoplast during leaf senescence and in membrane fusion during vacuole biogenesis in roots []. DMP8 and DMP9 have been shown to facilitate gamete fusion during double fertilization in flowering plants [].
