Probable inactive protein kinase that activates the YODA MAP kinase cascade, which regulates the asymmetric first division and embryo polarity, by promoting the elongation of the zygote and the development of its basal daughter cell into the extra-embryonic suspensor. Acts as an adapter at the plasma membrane, possibly by recruiting and binding an activator. Interacts with YDA. Expressed at the mRNA level in the sperm cells in mature pollen, but the protein is only detectable in the zygote and the micropylar endosperm upon fertilization. Transiently expressed at the protein level in the zygote upon fertilization. No longer detected by the time of the first division. The protein kinase domain is predicted to be catalytically inactive. Diacylation-mediated membrane association is essential for BSK12 function. BSK12 exerts a paternal effect on embryonic patterning. Transcripts produced but not translated in the sperm cells are delivered to the seed where they become translated, resulting in a transient accumulation of the protein in both products of the double fertilization, the zygote and the central cell. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.