Proteins are important building blocks of all cells and tissues. They form the structural part of most organs and make up enzymes and hormones that regulate body functions. Body fluids contain many different proteins that serve diverse functions, such as transport of nutrients, removal of toxins, control of metabolic processes, and defense against invaders. Protein electrophoresis is a method for separating these proteins based on their size and electrical charge. When the proteins in body fluids are separated by electrophoresis, they form a characteristic pattern of bands of different widths and intensities, reflecting the mixture of proteins present. This pattern is divided into five fractions, called albumin, alpha 1, alpha 2, beta, and gamma. In some cases, the beta fraction is further divided into beta 1 and beta 2. Albumin, which is produced in the liver, accounts for about 60% of the protein in the blood. "Globulins" is a collective term used to refer to proteins other than albumin. With the exception of the immunoglobulins and some complement proteins, most of the globulins are also produced in the liver. Immunofixation electrophoresis (IFE) is a method used to identify abnormal bands seen on serum, urine, or cerebrospinal fluid (CSF) protein electrophoresis, in order to determine which type of antibody (immunoglobulin) is present. The major plasma proteins and their functions are listed according to their electrophoretic group (the visible band that they are part of) in the table below titled Protein Groups.