Figure 2.

Crystal Structure of the MAM Domain of NRP1

(A) The crystal structure of the MAM domain in cartoon representation colored as a spectrum from blue to red from the N to the C terminus. The structure contains 10 β strands and three short α-helical turns. The two calcium atoms are shown as black spheres.

(B) The dimer within the asymmetric unit shown in cartoon representation with one chain in yellow and the second in green.

(C) The crystal structure of the MAM domain revealed two calcium-binding sites in close proximity. The calcium-binding sites are shown in stereo view. First Ca²⁺ (black sphere) is coordinated by E651, D685, N691, and D796 as well as a single water molecule (W1). The second Ca²⁺ is coordinated by two water molecules (W2 and W3), D685, and a bicine molecule present within the crystallization condition. The coordinate bonds are shown by black dashed lines. The water molecules are shown as blue spheres while amino acid side chains (yellow) and a bicine molecule (pink) are shown in stick representation. Electron density (2F_o − F_c) is contoured at 1.6 σ and represented as a wire mesh.