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© 1994 American Society of Plant Physiologists
(from Durso & Cyr 1994, Plant Cell, 6: 893-905)
Tubulin binding proteins (lane a; as shown in Figure 1, lane b) were chromatographed using a matrix of covalently immobilized CaM. A fraction of the tubulin binding proteins did not bind to the CaM affinity matrix in the presence of Ca2+ (lane b). However, pp50 did bind CaM in the presence of Ca2+, and it was among the proteins that eluted from the CaM affinity matrix when Ca2+ was removed from the matrix by EGTA. Such proteins are a Ca2+-dependent CaM binding subfraction of tubulin binding proteins and, hence, are designated 'tubulin/CaM binding proteins' (lane c). These tubulin/CaM binding proteins were assayed by cosedimentation to confirm that pp50 thus obtained retains its MT binding activity: lane d is the cosedimentation supernatant, and lane e is the cosedimentation pellet. The symbols at left are as given in Figure 1.
