Measurement of Oat Globulin by Radioimmunoassay

Abstract

Storage proteins, the proteins that accumulate during seed development, have been extensively studied because of their nutritional importance. For this reason, they are of interest to plant molecular biologists who would like to improve the amino acid composition of these proteins using genetic engineering technology. They are also of interest to developmental biologists because their accumulation during seed development and no other part of the plant life cycle provides such an excellent example of selective gene expression. In the effort to learn more about the structure, accumulation, and biosynthesis of storage proteins, the use of specific antibodies has been invaluable. For example, immunoaffinity columns have been used to isolate radiolabeled storage protein precursors from subcellular fractions, resulting in information about the site of synthesis and deposition into protein bodies (Chrispeels et al. 1982a, b). Antibodies have also been used to elucidate precursor-product relationships and posttranslational processing events for many different plant species. However, one of the most frequent uses of antibodies is to immunoprecipitate storage proteins from in vitro translation products. This technique is particularly useful when hybrid-select translation is used to identify specific messenger RNA molecules (McGrogan et al. 1979; Meinke et al. 1981). The most commonly used method of quantifying specific storage proteins during seed development has been immunoelectrophoresis (Weeke 1973; Sun et al. 1978; Crouch and Sussex 1981). However, the radioimmunoassay (RIA) (Felsted et al. 1982; Triplett and Quatrano 1982; Colyer and Luthe 1984) and a variation of the RIA (Domoney et al. 1980) using the ELSA technique have been used to quantify several other plant proteins.