BCHM 210 Midterm: Calmodulin
Document Summary
Calmodulin: calmodulin, a 17 kda protein, is a ca++ sensor, 2. Calmodulin is activated when the ca++ concentration exceeds 500 nm: 3. Calmodulin contains four ef hand motifs, a helix loop helix structure that binds ca+: 4. Calcium is ligated to 6 oxygen atoms atoms from the protein and a water molecule. The calcium is ligated to 6 oxygen atoms from the calmodulin protein and a water molecule. These two helices and the intervening loop form the ca2+ -binding motif. Seven oxygen atoms are coordinated to each ca2+, six from the protein and one from a bound water molecule. Each monomer consist of two subunits, and , linked by a disulfide bond. The two subunits together form a binding site for one insulin molecule. When insulin binds, the two subunits are held together. The -subunit, mostly inside the cell, is a tyrosine kinase that cross- phosphorylates the other monomer. Insulin and growth receptors are themselves kinases (tyrosine kinases)
