AKINα1, a Ser/Thr kinase from Arabidopsis thaliana belongs to the highly conserved SNF1 family of protein kinases in eukaryotes. Recent data suggest that the plant SNF1-related kinases (SnRK1 family) are key enzymes implicated in the regulation of carbohydrate and lipid metabolism. In Saccharomyces cerevisiae and mammals, the SNF1 and AMPKα protein kinases interact with two other families of proteins, namely SNF4/AMPKγ and SIP1/SIP2/GAL83/AMPKβ, to form active heterotrimeric complexes. In this paper, we describe the characterisation of three novel cDNAs. AKINβ1 and AKINβ2 encode proteins similar to SIP1, SIP2 and GAL83 and AKINγ codes for a protein showing similarity with SNF4. Using the two-hybrid system, specific interactions have been shown between A. thaliana AKINβ1/β2, AKINγ and AKINγ as well as between the A. thaliana and S. cerevisiae subunits. Interestingly, AKINβ1, AKINβ2 and AKINγ mRNAs accumulate differentially in A. thaliana tissues and are modulated during development and under different growth conditions. These data suggest the presence in higher plants of a conserved heterotrimeric complex. Moreover, the differential transcription of different non-catalytic subunits can constitute a first level of regulation of the SNF1-like complex in plants.