Lipid transfer protein that, together with LTPG2, binds to lipids and functions as a component of the cuticular lipid export machinery that performs extensive export of intracellular lipids (e.g. C29 alkane) from epidermal cells to the surface to build the cuticular wax layer and silique walls. Involved in the establishment of resistance to the necrotrophic fungal pathogen Alternaria brassicicola. Contributes to pre-invasive defense against some non-host powdery mildew pathogens by preventing the penetration of the epidermal cell wall by the fungal agents (e.g. Blumeria graminis f. sp. hordei (Bgh)) (PubMed:30102837). Maybe involved in seed and ovule maturation and development, probably by regulating the fatty acids homeostasis during suberin and sporopollenin biosynthesis or deposition (By similarity). Targeted to the plasma membrane via the vesicular trafficking system (PubMed:19321705, PubMed:22891199). Localized to the plasma membrane on all faces of epidermal cells (PubMed:19366900). Also detected in the periclinal cell wall (PubMed:19366900). In young meristematic cells, observed in plasma membrane and in puncta resembling the Golgi (PubMed:19366900). Localized to papillae at the sites of Blumeria graminis f. sp. hordei (Bgh) penetration (Bgh) (PubMed:30102837). Up-regulated in the epidermis of stems and leaves. Expressed in the epidermis, stem cortex, vascular bundles and mesophyll cells in root tips, cotyledons, seedlings, leaves, caulines, flowers, siliques, pollen, and early-developing seeds. Accumulates in seeds after imbibition (PubMed:23893219). High levels in the aerial portion of 10 days old seedlings. Accumulates in the epidermis during cuticle biosynthesis (e.g. in inflorescence stems). Also detected in flowers, in upper portion of the styles, pollen, veins of the sepals and petals, silique walls and seeds in the early stages of development (PubMed:23893219). In epidermis, present in trichomes, leaf mesophyll cells, and stem cortex and xylem. O-glycosylated on hydroxyprolines; noncontiguous hydroxylproline residues are glycosylated with arabinogalactan. Reduced cuticular wax load on the stem surface and in silique walls, with altered cuticular lipid composition (especially C29 alkane) associated with diffuse cuticular layer structure. Increased number of plastoglobules in the stem cortex and leaf mesophyll cells, protrusions of the cytoplasm into the vacuole in the epidermis, and enhanced susceptibility to infection by the necrotrophic fungal pathogen Alternaria brassicicola. Increased susceptibility to penetration of the epidermal cell wall by the non-host mildew fungal agent Blumeria graminis f. sp. hordei (Bgh) (PubMed:30102837). Belongs to the plant LTP family.