Probably involved in the receptor-like kinase-mediated signal transduction pathway. Homodimer or homooligomer. Interacts with PRK1. Expressed in mature pollen grains and pollen tubes, but not in style, ovary, petal, leaf, root or sepal. Detected around the time of microspore mitosis with a peak in mature pollen grains. The NAB domain is capable to bind actin filaments. Phosphorylated by PRK1.