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Tail-anchored (TA) proteins are a special class of membrane proteins that carry out vital functions in all living cells. Targeting mechanisms of TA proteins are investigated as the best example for post-translational protein targeting in yeast. Of the several mechanisms, Guided Entry of Tail-anchored protein (GET) pathway plays a major role in TA protein targeting. Many in silico and in vivo analyses are geared to identify TA proteins and their targeting mechanisms in different systems including Arabidopsis thaliana. Yet, crop plants that grow in specific and/or different conditions are not investigated for the presence of TA proteins and GET pathway. This study majorly investigates GET pathway in two crop plants, Oryza sativa subsp. Indica and Solanum tuberosum, through detailed in silico analysis. 508 and 912 TA proteins are identified in Oryza sativa subsp. Indica and Solanum tuberosum respectively and their localization with respect to endoplasmic reticulum (ER), mitochondria, and chloroplast has been delineated. Similarly, the associated GET proteins are identified (Get1, Get3 and Get4) and their structural inferences are elucidated using homology modelling. Get3 models are based on yeast Get3. The cytoplasmic Get3 from O. sativa is identified to be very similar to yeast Get3 with conserved P-loop and TA binding groove. Three cytoplasmic Get3s are identified for S. tuberosum. Taken together, this is the first study to identify TA proteins and GET components in Oryza sativa subsp. Indica and Solanum tuberosum, forming the basis for any further experimental characterization of TA targeting and GET pathway mechanisms in crop plants.

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Entry of Tail Anchored protein (GET) pathway is known to be the targeting machinery for C-terminal single pass membrane proteins (TA proteins). GET pathway components (GET1, GET2, GET3, GET4 and GET5) and its accessory proteins ensure the precise delivery of TA proteins. The mechanistic basis of this pathway is investigated considerably in Saccharomyces spp. Arabidopsis thaliana has four variants of GET3. Out of the four variants, AtGet3L, a chloroplast Get3 is being characterized in our study. This is the first Get3 structure from plant system. Crystal structure of AtGet3∆L was solved at 2.5Å resolution by molecular replacement method. The crystals of AtGet3ΔL belonged to space group P1 21 1 with unit cell parameters a= 59.25, b= 67.05, c= 99.40 Å, α= 90, β= 97.81 and γ=90°. The AtGet3ΔL structures is a dimer and share high degree of structural similarity with All4481 protein from Nostoc sp. PCC 7120. Presence of C-terminal HSP domain makes AtGet3ΔL unique among all reported Get3 structures and may be bypassing the interactions required for cytosolic Get3 for TA protein targeting.