 In the A-type lattice, the lateral associations of protofilaments occur between adjacent α and β-tubulin subunits (i.e.an α-tubulin subunit from one protofilament interacts with a β-tubulin subunit from an adjacent protofilament).In the B-type lattice, the α and β-tubulin subunits from one protofilament interact with the α and β-tubulin subunits from an adjacent protofilament, respectively.