Abstract
Abstract: Starch granules from the leaves of kidney bean (Phaseolus vulgaris L.), as well as from seeds, asso ciate the protein with the molecular mass of 59 kDa. Our previous study has shown that the 59 kDa-protein in seeds is granule-bound starch synthase I (PvGBSSIa) and that the transcript specifically accumulates to seeds. The determined N-terminal amino acid sequence of the 59 kDa protein in starch granules from leaves, GMKLIFVGMEVGP, was homologous to, but somewhat different from, that of PvGBSSIa. A cDNA clone (designated pvgbsslb) for the leaf protein (PvGBSSIb) was isolated from kidney bean leaves by reverse transcriptase-mediated PCR (RT-PCR), 5'-RACE (rapid amplification of cDNA end), and 3'-RACE. The pre dicted amino acid sequence of mature PvGBSSIb displayed significant identity (83%) to that of pea GBSSIb. Analysis of RT-PCR products indicated that the pvgbsslb transcripts predominantly accumulate in leaves. Recombinant PvGBSSIb was purified from Escherichia coil and some enzymatic properties were investigated.
