Abstract
The β-type carbonic anhydrase (PtCA1) localizes as clustered particles at the surface of the girdle lamellae in the marine diatom Phaeodactylum tricornutum. The PtCA1 gene (ptca1) contains 138 bp of 5'-sequence (pre138), which encodes an N-terminal presequence of 46 amino acids (Pre46AA). The Pre46AA comprises of an ER-signal, which is followed by a chloroplast transit region. However, the chloroplast transit region is yet to be addressed in detail. A series of truncations was carried out on the 3'-terminus of pre138. These truncated ptca1 were ligated with the GFP gene (egfp). As a result, a short motif, FNAN, around the ER cleavage site of Pre46AA was shown to be critical as a chloroplast transit. GFP analysis of N- or C-terminus truncations of the mature PtCA1 suggested that 1-20 region from C-terminus might participate in the particle formation of PtCA1.
