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Fibrillin-1 (PDB ID: 2W86) is a protein which is encoded in human bodies by the gene FBN1 situated on chromosome 15. Fibrillin-1 is a single protein chain from the class of glycoproteins with a mass of 350 kDa and it forms microfibrils located in the extracellular matrix. Thus, fibrillin-1 has a role in the structural support of cells in elastic and nonelastic connective tissue in the human body.
Fibrillin-1 (PDB ID: 2W86) is a protein which is encoded in human bodies by the gene FBN1 situated on chromosome 15. Fibrillin-1 is a single protein chain from the class of glycoproteins with a mass of 350 kDa and it forms microfibrils located in the extracellular matrix. Thus, fibrillin-1 has a role in the structural support of cells in elastic and nonelastic connective tissue in the human body.


TWO cb-EGF units
 


<scene name='86/868178/Ca_cation_binding/2'>Ca 2+ binding
<scene name='86/868178/Ca_cation_binding/2'>Ca 2+ binding
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== Structure ==
== Structure ==
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 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 cb-EGF contain 6 residues of cysteine which form 3 disulfide bridges (Proteopedia 3D visualization of disulfide bridges) stabilizing the secondary structure of the protein and a Ca2+ binding site D/N-x-D/N-E/Q-xm-D/N-xn-Y/F where x, xm, et xn represent certain number of amino acids between amino acids included directly in Ca2+ binding. Amino acids which participate in the Ca2+ binding D, N, E, Q containing 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.
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 3 disulfide bridges (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 Ca2+ binding site 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.
== Disease ==
== Disease ==