Qy. Liu et al., A GAMETOPHYTE CELL-WALL PROTEIN OF THE RED ALGA PORPHYRA-PURPUREA (RHODOPHYTA) CONTAINS 4 APPARENT POLYSACCHARIDE-BINDING DOMAINS, Journal of phycology, 32(6), 1996, pp. 995-1003
A complementary DNA (cDNA) clone from a Porphyra purpurea (Roth) C. Ag
ardh gametophyte-specific subtracted cDNA library was found to encode
a protein containing a signal peptide and four very similar regions wi
th a high degree of amino acid sequence similarity to the cellulose-bi
nding domains of fungal cellulases. Northern hybridization analysis in
dicated that the messenger RNA of this cDNA is highly abundant in the
gametophyte but not detectable in the sporophyte. In vitro translation
of the cDNA in the presence of canine pancreatic microsomes demonstra
ted that the signal peptide is capable of directing the protein into t
he endoplasmic reticulum where it is glycosylated. Because these obser
vations suggested a possible role as a gametophyte-specific cell wall
protein, cell wall proteins were isolated and a major protein having a
molecular weight similar to that estimated for the encoded protein wa
s purified. N-terminal sequence analysis indicated that his was the pr
otein encoded by the cDNA. The abundance and organization of this prot
ein suggest a role as a cell wall structural protein involved in cross
linking polysaccharides.