Abstract:The specific protein P2，one of the three specific proteins(P1，P2 and P3)in chloroplasts from photoperiod-sensitive genlc malesterile rice previously reported was purlfied through preparative two dimensional gel electrophoresis and preparatwe isoelectric 10-CUSlng(1EF) and from which an uniform P2，checked with SDS-PAGE and IEF，was obtained．The molecular weight and isoelectric point was 61 kD and 5，8，respectively．Therefore P2 was referred as P61．A search in databases revealed that the aminoterminal sequence Of P61 was identical to that of perb unit of chloroplast ATP ase from barley and rice