The cells of plants are coated with an outer layer called a cuticle that helps protect against water loss, frost, ultraviolet radiation, and damage from insects.  The cuticle primarily consists of a molecule called cutin, which is composed of wax molecules linked together.  These wax precursors of cutins are produced and linked together in the cytoplasm to form functional cutin, which is then exported to the extracellular matrix.Researchers interested in characterizing the proteins involved in transporting cutin to the extracellular matrix created several mutant lines of the plant Arabidopsis thaliana.  Lines with defects in the gene designated dso (which encodes the DSO protein) manifested abnormalities in the cuticle.  The DSO protein is hypothesized to be localized to lipid rafts in the plasma membrane.  To determine how the DSO protein is involved in cuticle formation, cutin was isolated from wild-type and dso-mutant plants and hydrolyzed into its precursor components.  The precursors were then analyzed by gas chromatography and mass spectrometry.  Levels of several classes of cutin precursors were obtained from the cuticles (Table 1).Table 1  Levels of Several Cutin Precursor Classes Found in Wild-Type and dso-Mutant Arabidopsis thaliana CuticlesAdapted from Panikashvili D, Savaldi-Goldstein S, Mandel T, et al. The Arabidopsis DESPERADO/AtWBC11 transporter is required for cutin and wax secretion. Plant Physiol. 2007;145(4):1345-1360. Question 42Based on the hypothesized localization of DSO proteins, the region of the plasma membrane that surrounds DSO is most likely rich in which of the following molecules relative to other plasma membrane regions?A.SterolsB.PhospholipidsC.ProstaglandinsD.Triglycerides