(Solved): Toll-like receptors are part of a protein kinase cascade. The CD14 protein (for cluster of differe ...

Toll-like receptors are part of a protein kinase cascade. The CD14 protein (for cluster of differentiation) is a membrane protein that binds to the toll-like receptor. Among the molecules that stimulate this pathway are bacterial and fungal cell wall fragments. Binding of these fragment molecules to the receptor sets in motion a cascade of molecular changes that results in a change in the three-dimensional structure of the transcription factor NF-kB. (NF-kB stands for nuclear factor kappa light chain enhancer of activated B cells. It is a key transcription factor in the activation of both the nonspecific and specific immune systems.) The shape change allows NF-kB to enter the nucleus, bind to the promoters of genes, and activate the transcription of genes encoding defensive proteins. A genetic mutation that changes the structure of \( N F-\kappa B \) would be dangerous because Transcription would be blocked because this transcription factor could not enter the nucleus. The specific immune system would be affected, although the non-specific immune system would be spared. CD14 would not be able to initiate the protein kinase cascade, thus blocking transcription of defensive proteins.