GRV2 (GRAVITROPISM DEFECTIVE 2); binding / heat shock protein binding; GRV2 has sequence similarity to the C. elegans protein RME-8 which is involved in endocytosis. grv2 mutants result in a reduction in gravitropic response in hypocotyls and shoots but do not affect root gravitropism. The mutants are defective in amyloplast sedimentation. (2554 aa)