Transport protein are a large class of membrane proteins that mediate chemicals and signal exchange inside and outside the biofilm. Lipid bilayers form a hydrophobic barrier around cells or organelles that isolates them from their surroundings. Although some small molecules can penetrate directly through the membrane, most hydrophilic compounds, such as sugars, amino acids, ions, drugs, etc., require the help of specific transport protein to pass through the hydrophobic barrier. Therefore, transport protein play an important role in a wide range of cellular activities such as nutrient uptake, metabolite release, TCR repertoire and signal transduction.
Transport protein have many transport proteins in the inner membrane of chloroplasts, called transport protein. Their function is to selectively transport molecules into and out of chloroplasts. Transport of all transport protein in the chloroplast inner membrane is driven by concentration gradients rather than active transport. This is not only different from the transport proteins in the cytoplasmic membrane, but also different from the transport system in the mitochondrial inner membrane. There are also active transport proteins in the mitochondrial inner membrane and the scFv repertoire. An important transport mechanism of chloroplast transport protein is the exchange of "Pi transport protein" through which Pi and phosphoglycerin can be transported simultaneously. Chloroplast photosynthesis requires a large amount of inorganic phosphorus, and a large amount of intermediate 3-phosphoglyceric acid (3PGAL) is released. The phosphoric acid exchange carrier protein in the chloroplast inner membrane can transfer the inorganic Pi in the cytoplasmic membrane to the chloroplast matrix through the exchange and release the 3PGAL formed in the chloroplast matrix into the cytoplasm. Phosphate exchange transport protein are the most abundant proteins in the inner membrane of chloroplasts, accounting for about 12% of the total inner membrane proteins.
On June 5, 2014, Tsinghua University announced that the crystal structure of human glucose transporter GLUT1 was first analyzed by Professor Yan Ning's research team of Tsinghua University Medical College in the world, and its working mechanism and pathogenesis of related diseases were preliminarily revealed. This research achievement has been praised as a "milestone" major scientific achievement by the international academic circles. Yan Ning's research team started the GLUT1 study in 2009. In the past five years, they have made bold innovations, made important breakthroughs in research ideas and experimental techniques, and established China's leading edge in the forefront of structural biology. Human transmembrane transport of glucose has been studied for about 100 years. GLUT1, a glucose-transporting protein, was first isolated from red blood cells in 1977, but its gene sequence was identified in 1985. Since then, obtaining the three-dimensional structure of GLUT1 to truly understand its transport mechanism has become the frontier and the most difficult research hotspot in this field. In the past few decades, many of the world's top laboratories in the United States, Japan, Germany, the United Kingdom and other countries have been or are trying to tackle this problem, but have never succeeded.
It is reported that this achievement is not only a major breakthrough in the study of peptide repertoire in the glucose transport protein , but also provides an important molecular basis for understanding the transport mechanism of other glucose transport protein with important physiological functions just like the bound antibodies, revealing the process of life-sustaining substances entering the cell membrane and transporting them into the human body. It is of great guiding significance to understand the life process step by step. Professor Lu Bai of Tsinghua University Medical College said, "The significance of this achievement lies in two aspects. First, from the point of view of scientific research, the first reveals the structure of human transport protein, which can help people understand the most basic process of molecular transport in life science. From a clinical point of view, it is helpful to understand the pathogenesis of epilepsy, cancer and diabetes in young children, and can be used as a potential target for drug research and development. After the results were published in the Journal Nature, 2012 Nobel Prize laureate Bryan Klebica said, "The structure of mammalian membrane proteins is much more difficult than that of bacterial homologous proteins because of the anti-idiotypic antibodies, so the structure of mammalian membrane proteins obtained so far is very few. But to develop drugs for human diseases, it is very important to obtain the structure of human transport protein. Structural analysis of GLUT1 itself is a challenging and risky task, so it is a great achievement. As for the production of anti idiotypic antibodies Ronald Cabeck, a professor at the University of California, Los Angeles and a specialist in transporter protein research, said, "Academia has studied the structure of GLUT1 for half a century, and Yanning was the first person in the world to obtain the crystal structure of GLUT1. To some extent, she has overcome the past 50 years to engage in it." All the scientists involved in the study. This is also the first human transporter structure ever obtained and represents an important technological breakthrough just like the Fab repertoire. The results are self-evident for the study of cancer and diabetes. Harvey Laudish, a professor at the Massachusetts Institute of Technology and a member of the American Academy of Sciences and the cloning of GLUT1 gene, said, "This is a very important achievement that has finally revealed clearly the 12 transmembrane structures and transport mechanisms of GLUT1, which has been speculated for 30 years since the cloning of the gene.