Final answer:
Hsp70-like proteins assist in the proper folding of proteins within cells by controlling their unfolding and refolding, and are crucial during stress conditions like increased temperatures when they help refold misfolded proteins to maintain their functionality.
Step-by-step explanation:
Hsp70-like proteins play a crucial role in the folding of proteins within cells, affecting existing interactions between proteins. An example of their influence is seen during the transportation of mitochondrial proteins from the cytoplasm into the mitochondrial matrix. The mitochondria's membrane presents a barrier that a folded protein cannot cross by itself. The HSP70 protein acts as a chaperone by controlling the unfolding of this protein as it enters the matrix, allowing it to pass through the membrane. After the transfer, another HSP70 molecule inside the mitochondrion assists in the refolding process, giving the protein a biologically active shape.
Heat shock proteins, including HSP70, are critical for cell survival during stress. They activate in response to conditions such as increased temperatures, where they assist in the refolding of misfolded proteins, thereby preventing loss of function. This process is important because the three-dimensional structure of proteins determines their functionality, and without correct folding, proteins may lose their activity.