Differential expression of the soybean BiP gene family.

The soybean binding protein (BiP) gene family consists of at least four members designated soyBiPA, soyBiPB, soyBiPC and soyBiPD. We have performed immunoblotting of two-dimensional (2D) gels and RT-PCR assays with gene-specific primers to analyze the differential expression of this gene family in various soybean organs. The 2D gel profiles of the BiP forms from different organs were distinct and suggested that the BiP genes are under organ-specific regulation. In fact, while all four BiP transcripts were detected in leaves by gene-specific reverse transcriptase-polymerase chain reaction (RT-PCR) assays, different subsets were detected in the other organs. The soyBiPD was expressed in all organs, whereas the expression of the soyBiPB was restricted to leaves. The soyBiPA transcripts were detected in leaves, roots and seeds and soyBiPC RNA was confined to leaves, seeds and pods. Our data are consistent with organ-specific expression of the soybean BiP gene family.