Affects actin polymerization through interaction with the actin-binding protein CAP32/34 (acpA/acpB). Acts as a chaperone by stimulating the refolding of denaturated acpA and acpB, but neither stimulates nor inhibits the capping activity of native CAP32/34. Interacts with the heterodimeric F-actin-capping protein CAP32/34 (acpA/acpB). Binds via its C-terminal tail and interaction is ATP-dependent. Found in F-actin-rich regions of the cell cortex and cell protrusions. Heat shock cognate proteins are expressed constitutively during normal development. Up-regulated in aspidocytes, a resistant cell type induced from amoebae by a range of toxins including heavy metals and antibiotics. Belongs to the heat shock protein 70 family.