Characteristics of the chitin-synthesizing system of insect tissue.

Results obtained from isotopic dilution experiments are consistent with the operation of the chitin pathway as it has been established in fungal preparations. The last enzyme in this pathway, namely chitin synthase, seems to be accessible to substrate from the cell exterior, indicating its presence in the plasma membrane. It can, however, only be saturated (in a manner that partially excludes reaction with a competing substrate) from the cell side of the membrane.