Cloning and characterization of a pollen-specific cDNA encoding a glutamic-acid-rich protein (GARP) from potato Solanum berthaultii.
A pollen-specific cDNA was isolated from a cDNA library of in vitro germinated pollen of the diploid potato species Solanum berthaultii. The cDNA clone, designated SB401, hybridizes to a messenger RNA of 1.2 kb length in mature and germinated pollen. SB401 messenger RNA is absent from other parts of the plant, including other flower tissues. SB401 cDNA, which possesses a long stretch of AT-rich 5'-untranslated leader sequence, encodes a glutamic acid-rich protein (GARP) which is hydrophilic throughout and contains six imperfect repeated motifs of the sequence V-V-E-K-K-N/E-E with the di-basic amino acid residue pair (K-K) as the core within the repeats. These repeats are spaced at irregular intervals and predicted to form an alpha-helical structure. The SB401 protein was over-expressed in Escherichia coli and the purified protein was used for raising antiserum. Both E. coli-expressed and the endogenous SB401 proteins in pollen and pollen tubes appear much larger on SDS-polyacrylamide gels than their calculated molecular masses. Immunoblotting revealed the protein to be most abundant in germinated pollen. The structural features of SB401 protein and a possible role for the protein in pollen development, pollen germination, and pollen tube growth are discussed.
Liu
J
J
Max-Planck-Institut für Züchtungsforschung, Köln, Germany.
Seul
U
U
Thompson
R
R
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004926:Escherichia coli; D015723:Gene Library; D017343:Genes, Plant; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000096:biosynthesis* / Q000737:chemistry; D011058:Pollen; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D012091:Repetitive Sequences, Nucleic Acid; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; D010940:Plant Proteins; D011994:Recombinant Proteins; C104660:glutamic-acid-rich protein, Solanum berthaultii