Jh. Mu et al., CHARACTERIZATION OF A POLLEN-EXPRESSED RECEPTOR-LIKE KINASE GENE OF PETUNIA-INFLATA AND THE ACTIVITY OF ITS ENCODED KINASE, The Plant cell, 6(5), 1994, pp. 709-721
From a pollen tube cDNA library of Petunia inflata, we isolated clones
encoding a protein with structural features and biochemical propertie
s characteristic of receptor-like kinases. It was designated PRK1 for
pollen receptor-like kinase 1. The cytoplasmic domain of PRK1 is highl
y similar to the kinase domains of other plant receptor-like kinases a
nd contains nearly all of the conserved amino acids for serine/threoni
ne kinases. The extracellular domain of PRK1 contains leucine-rich rep
eats as found in some other plant receptor-like kinases, but overall i
ts sequence in this region does not share significant similarity. Char
acterization of a gene encoding PRK1 revealed the presence of two intr
ons. During pollen development, PRK1 mRNA was first detected in anthem
containing mostly binucleate microspores; it reached the highest leve
l of mature pollen and remained at a high level in in vitro-germinated
pollen tubes. The recombinant cytoplasmic domain of PRK1 autophosphor
ylated on serine and tyrosine, suggesting that PRK1 may be a dual-spec
ificity kinase. Monospecific immune serum to the recombinant extracell
ular domain of PRK1 detected a 69-kD protein in microsomal membranes o
f pollen and pollen tubes. The characteristics of PRK1 suggest that it
may play a role in signal transduction events during pollen developme
nt and/or pollination.