Interaction of alkali light chain 1 with the isolated 20-kilodalton fragment of myosin subfragment-1 heavy chain and F-actin.
The binding of one of the alkali light chains of myosin, A1, with the isolated renatured 20-kDa fragment of myosin subfragment-1 heavy chain was demonstrated by means of difference UV absorption spectroscopy. The difference spectrum with either rabbit or chicken A1 showed two characteristic peaks at 279 and 287 nm indicating a perturbation of tyrosyl chromophores by the association with the 20-kDa fragment. The delta epsilon at 287 nm increased with an increase in the molar ratio of A1/20-kDa fragment and reached a maximum value at around equimolar ratio. The maximum delta epsilon value was approximately three times larger with rabbit A1 than with chicken A1. Based on the positions of Tyr residues in the amino acid sequences, the contact surface of A1 with myosin heavy chain was concluded to be spread over a large area of A1. The binding of 20-kDa fragment with F-actin was measured by following the increase in turbidity. The affinity appeared to increase several times in the presence of A1. A1 may possibly control the affinity of myosin for actin.
Katoh
T
T
Department of Chemistry, Faculty of Science, Hokkaido University.
Katoh
H
H
Morita
F
F
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002645:Chickens; D008970:Molecular Weight; D009218:Myosins / Q000378:metabolism*; D011485:Protein Binding; D011817:Rabbits; D013056:Spectrophotometry, Ultraviolet
D000199:Actins; D009218:Myosins