Abstract Profilin is a small actin-binding protein and is expressed at high leve
ID: 261177 • Letter: A
Question
Abstract
Profilin is a small actin-binding protein and is expressed at high levels in mature pollen where it is thought to regulate actin filament
dynamics upon pollen germination and tube growth. The majority of identified plant profilins contain a MAP kinase phosphorylation
motif, P–X–T–P, and a MAP kinase interaction motif (KIM). In in vitro kinase assays, the tobacco MAP kinases
p45Ntf4 and SIPK, when activated by the tobacco MAP kinase kinase NtMEK2, can phosphorylate the tobacco profilin NtProf2.
Mutagenesis of the threonine residue in this motif identified it as the site of MAP kinase phosphorylation. Fractionation of tobacco
pollen extracts showed that p45Ntf4 is found exclusively in the high-speed pellet fraction while SIPK and profilin are predominantly
cytosolic. These data identify one of the first substrates to be directly phosphorylated by MAP kinases in plants.
Answer the question based on the above text:
Did the abstract state the overall research question, brief materials and methods used to address question, describe results and relate findings to field?
Explanation / Answer
Yes the overall research question was identification of profilins that regulate the actin filament dynamics during pollen germination and tube growth. Briefly the materials and methods include in vitro kinase assays and mutagenic experiments to identify the differences in motif patterns and high speed centrifugation/gradient centrifugation to separate the fractions. Results demonstrate their site of presence (cytosol) and substrates which would be phosphorylated by MAP kinases.