7. Prospects and Conclusions
As is the case for many protein families containing multiple paralogs in a species, the GLUT family of proteins exerts essential physiological functions that need be delicately regulated. Multiple proteins with overlapping molecular functions provide a cushion for genetic, physiological and environmental disturbance. At the same time, tissue specific distribution of these transporters allows the fine tuning of expression to the tissue specific condition. Studies on the details of this fine regulation have just started. Much remains to be investigated. It would not be surprising if some day findings indicate that a specific GLUT is a limiting factor to the development of a specific cell type. Physiological and genomic evidence indicate that the regulation of glucose homeostasis in avians is distinct from the mammalian counterpart. Further examination of GLUT members in birds will shed new light on the function of these family.