Abstract:A protein (PI) from a photoperiod-sensitive genic male sterile (PSGMS) mutant of rice ( Oryza sativa L. ), Nongken 58S, was purified with preparative two-dimensional gel electrophoresis. Uniform P1, checked by SDS-PAGE and isoelectric focusing (IEF), was obtained. Its molecular weight and isoelectric point was 41 kD and 6.2, respectively. Here, P1 was referred to P41. Analysis of N-terminal sequence and a search in SWISSPROT database revealed that P41 was homologue to β subunit of ATP synthase from rice and yeast transcription factor CAD1, respectively. Besides, P41 had a short glycine-rich sequence that was similar to the multifunctional motif in the highly conserved catalytic core of protein kinases.