Sandbox Reserved 1645: Difference between revisions

The protein contains multiple subunits called epidermal growth factor (EGF) and transforming growth factor β binding protein-like domain (7 TGF-bp). EGF are repeated in tandem along the whole protein which represents about 75% of the total fibrillin-1 lenght and they are interrupted by the insertion of TGF-bp unit. In total, there are 47 motifs of EGF in one fibrillin-1, but only 43 of them contain calcium binding sequences. In consequence, these EGF are named cb-EGF for their ability to bind calcium cations (Proteopedia 3D visualization of two tandem cb-EGF). Each of EGF or cb-EGF unit contains 6 residues of cysteine which form <scene name='86/868178/Disulfide_bridges/1'>3 disulfide bridges</scene> (CYS1-CYS3,CYS2-CYS4,CYS5-CYS6)(Proteopedia 3D visualization of disulfide bridges) stabilizing the secondary structure of the protein. cb-EGF units contain also a <scene name='86/868178/Ca_binding_site/1'>Ca2+ binding site</scene> composed by aminoacids D,N,Q,E,Y and F which participate into the cation bonding and which can be seperated by different number of other aminoacids (D/N-x-D/N-E/Q-xm-D/N-xn-Y/F represents the binding site of Ca2+,x, xm, and xn represent certain number of amino acids). Amino acids which participate in the Ca2+ binding D, N, E, Q contain oxygen in their lateral chains and Y with F which contain an aromatic cycle. Oxygen atoms of D/N/Q/E are involved in the Ca2+ binding and create the binding site with the pentagonal bipyramidal geometry.