Immunoprecipitation of 170-kD myosin with
antiserum against the 170-kD heavy chain. A, The 170-kD myosin was
mixed with the antiserum without (a and c) or with (b and d) 1.5
mm CaCl2 and subsequently mixed with protein
A-conjugated beads. Specimens were centrifuged at 500g
for 3 min. The materials bound to the beads were analyzed by SDS-PAGE
on a 6% polyacrylamide gel (a and b) or by immunoblotting using
antiserum against spinach CaM (c and d). B, The 170-kD myosin was mixed
with antiserum against the 170-kD heavy chain without the addition of
1.5 mm CaCl2 and subsequently mixed with
protein A-conjugated beads. After the beads were washed with KEMP
solution containing either EGTA (a) or Ca2+ at
concentrations of 10−7 m (b),
10−6 m (c), 10−5 m
(d), or 10−4 m (e), the 18-kD polypeptide
associated with the beads was detected by the immunoblotting using the
antiserum against spinach CaM. The arrow and arrowhead indicate the
170-kD heavy chain and the 18-kD polypeptide, respectively.
Mrs (×10−3) of standard
proteins are indicated on the left.