Nw. Ohan et al., HEAT-SHOCK-INDUCED ASSEMBLY OF HSP30 FAMILY MEMBERS INTO HIGH-MOLECULAR-WEIGHT AGGREGATES IN XENOPUS-LAEVIS CULTURED-CELLS, Comparative biochemistry and physiology. B. Comparative biochemistry, 119(2), 1998, pp. 381-389
In this study, we have examined whether members of the small heat shoc
k protein family, hsp30, were capable of forming heat-induced aggregat
es in Xenopus laevis A6 kidney epithelial cells. Race-zonal centrifuga
tion coupled with immunoblot analysis demonstrated the presence of hsp
30 aggregates with an estimated sedimentation coefficient of 10-16S. A
lso, pore exclusion limit electrophoretic analysis of labeled protein
from heat-shocked A6 cells revealed four heat-induced aggregates, incl
uding a prominent 510 kDa aggregate, as well as weaker 350, 290, and 2
40 kDa aggregates. Immunoblot analysis of the aggregates employing an
hsp30C antibody suggested that the 510 and 350 kDa aggregates were com
prised of hsp30 protein. One- and two-dimensional SDS-PAGE analysis of
the proteins isolated from the 510 kDa region of the pore exclusion l
imit electrophoretic gel confirmed the presence of 30 kDa heat-induced
protein. A total of eight small hsps were present in this aggregate,
suggesting that virtually all of the major small hsps in Xenopus A6 ce
lls were involved in aggregate formation. This study also detected the
presence of heat-inducible hsp70 in the 510 kDa gel fraction containi
ng the small hsps, but it could not be determined whether it was part
of the multimer complex. (C) 1998 Elsevier Science Inc.