juxtamembrane and transmembrane (JMTM) domain found in the amyloid-beta precursor protein (APP) family
The amyloid-beta precursor protein (APP) family includes amyloid-like proteins APLP-1 and APLP-2. APP (also called ABPP, APPI, Alzheimer disease (AD) amyloid protein, amyloid precursor protein, amyloid-beta A4 protein, cerebral vascular amyloid peptide (CVAP), PreA4, or protease nexin-II (PN-II)) functions as a cell surface receptor and performs physiological functions on the surface of neurons relevant to neurite growth, neuronal adhesion and axonogenesis. Amyloid-beta peptides are lipophilic metal chelators with metal-reducing activity; they bind transient metals such as copper, zinc and iron. APLP-1, also called APLP, may play a role in postsynaptic function. It couples to JIP signal transduction through C-terminal binding. APLP-1 may interact with cellular G-protein signaling pathways. It can regulate neurite outgrowth through binding to components of the extracellular matrix such as heparin and collagen I. APLP-2 (also called amyloid protein homolog (APPH), or CDEI box-binding protein (CDEBP)) may play a role in the regulation of hemostasis. Its soluble form may have inhibitory properties towards coagulation factors. APLP-2 may bind to the DNA 5'-GTCACATG-3'(CDEI box). It inhibits trypsin, chymotrypsin, plasmin, factor XIA, and plasma and glandular kallikrein. This model corresponds to juxtamembrane and transmembrane (JMTM) domain of APP, which consists of the intact transmembrane (TM) domain with adjacent N-terminal juxtamembrane (JM) region. More than half of all familial APP mutations of Alzheimer's disease are seen in its JMTM domain region.