Plants synthesize thousands of specialized metabolites that are crucial for plant survival. Glucosinolates are specialized defence-metabolites found in plants of the order Brassicales including the model plant Arabidopsis thaliana. Tissue-specific accumulation of glucosinolates is an essential part of plant defence, and the distribution pattern reflects the individual contributions from biosynthesis, transport and turnover. However, little is known about how and to what extent transport processes contribute to establishing these distribution patterns. With the recent identification of AtGTR1 and AtGTR2, two high-affinity glucosinolate transporters, a new molecular tool was provided to study glucosinlate transport in A. thaliana. This thesis contains 6 papers where transporter proteins are identified and characterized biochemically and genetically.