Thiamine is a vitamin, also called vitamin B1. All organisms use thiamine, but it is made only in bacteria, fungi, and plants. Animals must obtain it from their diet, and thus, for humans, it is an essential nutrient. Uptake of thiamine by cells occurs via facilitated transport. In human, two members of the SLC gene family of transporter proteins, SLC19A2 and SLC19A3, are capable of the thiamine transport. In yeast, three transporters have been described.
Jérôme Savocco, Sylvain Nootens and colleagues working in the lab of Pierre Morsomme (LIBST) have studied the regulation of yeast thiamine transporters. They found that the thiamine transporters are actively endocytosed when thiamine is present in the external medium. They discovered that dedicated proteins from the endocytic machinery are controlling the abundance of thiamine transporters at the plasma membrane. Whether this mechanism is also present in human cells has still to be determined but this study shows once more how yeast can be used as a model system to understand cell biology. The study has been published in the journal PLoS Biology.