In nature, all living cells are surrounded by a biological membrane which acts as a barrier between the external and the internal environment. The membrane is impermeable to most water-soluble molecules and is composed of a phospholipid bilayer in which protein molecules are embedded (integral membrane proteins). A large group of integral membrane proteins are involved in solute and vitamin transport across the lipid bilayer either by import or export process. The uptake of organic micronutrients, such as B-type vitamins is essential in auxotrophic organisms, which are not capable of synthesizing these essential compounds. The B-type vitamin family includes eight different B-type vitamins (vitamin B1, B2, B3, B5, B6, B7, B9 and B12). And, to transport these respective vitamins, various membrane transporter are responsible, one of reported family is Pnu transporter. The work presented in this thesis describe detailed biochemical and functional information about Pnu membrane transporters. The Pnu membrane transporter are responsible for B-type vitamin transport, inside the membrane without any ATP hydrolysis. The thesis includes various techniques such as molecular biology, biochemistry and structure biology to understand the B-type vitamin transport process in detail.