Holappa LD, Walker-Simmons MK (1997) The wheat protein kinase gene, TaPK3, of the PKABA1 subfamily is differentially regulated in greening wheat seedlings. Plant Molecular Biology 33:935-941.

We have identified a new wheat protein kinase gene, TaPK3, that is expressed in greening wheat seedlings. TaPK3 has high sequence homology to wheat PKABA1 protein kinase, which is upregulated by cold-temperature, dehydration and abscisic acid (ABA). Like the PKABA1 protein kinase mRNA, TaPK3 encodes a predicted polypeptide with all twelve conserved catalytic subdomains characteristic of serine/threonine protein kinases and contains an aspartic acid amino acid stretch near the carboxyl-terminus. Comparison of the deduced amino acid sequences indicates that TaPK3 and PKABA1 have high sequence homology (97% similarity) except for sequence diversity at the 3'-end, where TaPK3 has a 37 bp deletion and an additional 135 bp in the translated sequence. Use of a TaPK3 gene-specific probe has revealed that TaPK3 is differentially expressed with respect to PKABA1. TaPK3 mRNA accumulates in greening shoot tissue of wheat, but is not affected by dehydration, cold-temperature treatment or ABA. Based on sequence and expression differences, we conclude that expression of the PKABA1-like protein kinases is not limited to stress responses.