Regulatory subunit of the probable trimeric SNF1-related protein kinase (SnRK) complex, which may play a role in a signal transduction cascade regulating gene expression and carbohydrate metabolism in higher plants. The SnRK complex may also be involved in the regulation of fatty acid synthesis by phosphorylation of acetyl-CoA carboxylase and in assimilation of nitrogen by phosphorylating nitrate reductase. Subunit of a probable heterotrimeric complex consisting of an alpha catalytic (KIN10 or KIN11) subunit, and a beta (KINB) and a gamma (KING or SNF4) non-catalytic regulatory subunits (PubMed:17028154, PubMed:25736509). Interacts with SNF4 and CBL1. Interacts with FLZ1, FLZ2, FLZ8, FLZ9, FLZ10, FLZ12, FLZ13, FLZ14 and FLZ15 (PubMed:29945970). A number of isoforms are produced. According to EST sequences. Expressed in vegetative organs and, to lower extent, in reproductive organs. Rapidly and strongly induced in the dark, quickly repressed by light. Kinase-interacting sequence (KIS) is specific for the alpha catalytic subunit interaction and Association with SNF1 Complex (ASC) is specific for the gamma non-catalytic regulatory subunit interaction. Sumoylated by SIZ1. Belongs to the 5'-AMP-activated protein kinase beta subunit family.