The protein is known as mBDNF, which stands for mature brain-derived neurotrophic factor. In an earlier study, another team of NICHD researchers had shown that mBDNF is essential for the formation of long-term memory, the ability to remember things for longer than a day.
“Understanding how BDNF is made may help us to better understand the learning process, perhaps leading to better treatments for disorders of learning and memory,?said Duane Alexander, M.D., Director of the National Institute of Child Health and Human Development.
The research team was led by Y.Peng Loh Ph.D, of NICHD’s Section on Cellular Neurobiology. The researchers published their work in the January 20 issue of Neuron.
Specifically, the researchers discovered that the enzyme carboxypeptidase E, (CPE) is needed to deliver the early, or inactive, form of BDNF ?proBDNF ?to a special compartment in the neuron (nerve cell.) Once in the compartment, proBDNF is chemically converted into active mBDNF. After mBDNF is formed, it is released to the outside of the neuron, where it binds to receptors on other neurons and stimulates them to form long-term memory.
Dr. Loh explained that, like other proteins, proBDNF is made inside the endoplasmic reticulum, a convoluted network of tubes and channels inside the cell. The proBDNF winds through the endoplasmic reticulum until it reaches another structure within the cell, the golgi apparatus. There, the proBDNF binds to CPE, which protrudes from special rafts of fatty, cholesterol-rich molecules known as lipids. If this binding process does not take place, proBDNF cannot be converted to its active form. Dr. Loh explained that the proBDNF molecule has four projection