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Cloning and characterization of a maize pollen-specific calcium-dependent calmodulin-independent protein kinase

Estruch, J.J., Kadwell, S., Merlin, E., Crossland, L.
Proceedings of the National Academy of Sciences of the United States of America 1994 v.91 no.19 pp. 8837-8841
Zea mays, messenger RNA, structural genes, complementary DNA, calcium, amino acid sequences, gene expression, pollen tubes, transcription (genetics), nucleotide sequences, pollen, inorganic ions
A calcium-dependent calmodulin-independent protein kinase (CDPK) has been cloned from maize (Zea mays). The sequence predicts a 550-amino acid (predicted molecular mass is 60 kDa) protein with two major functional domains: an N-terminal catalytic domain highly homologous to protein kinases and a C-terminal domain resembling calmodulins. Northern analysis shows that the expression of the maize CDPK gene is pollen specific and that its transcription is restricted to late stages of pollen development. Western blots reveal a major abundance of CDPK protein at the stage of pollen germination. In vitro germination and pollen tube growth are impaired upon addition of a calmodulin antagonist (calmidazolium), CDPK inhibitors (W-7), and antisense oligonucleotides directed against CDPK mRNA. These observations indicate that the function of the pollen-specific maize CDPK protein is required for germination and pollen tube growth.