A model is presented which explains the biological role of the leader peptide in protein export. Along the lines of this model, the conformational changes of a protein with environment serves as a general mechanism for translocation. The leader peptide in the cytoplasm takes a hairpin like conformation which reverts to an extended helix upon integration into the membrane. The essential features of this model are in accord with recent results of protein export.
A sensitive and rapid ELISA for quantitation of seed globulins is described. This method employs conjugation of pigeon pea ( Cajanus cajan ) globulin antibodies and the enzyme peroxidase together with dextran. Using this conjugate, proteins as low as 0.1 ng were detected. Dextran conjugate has a ten-fold greater efficiency of quantitating pigeon pea globulins than the commercial goat anti-rabbit IgG conjugate, and is three-fold more efficient than pigeon pea globulin IgG peroxidase conjugate. The method can be conveniently adapted for quantitation of other proteins also.
Using antibodies raised in rabbits, radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) are standardized for cowpea (var. Pusa Barsati) seed globulins. The RIA, when used to screen three stages of seed development, reveals that maximum globulins are detected at 28 days after flowering. When three different varieties of cowpea are assayed for their globulin content by RIA and ELISA, it is observed that the Bold Grain cowpea has the highest amount of related globulin as compared to two other varieties, namely Pusa Phalgun and Asparagus Bean.