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The Na,K-ATPase, an αβ hetero-oligomer, maintains the gradients of Na and K across the cell membrane vital to all animal cells. While the function of its catalytic α-subunit is well understood the role of β for transport and even tissue specific assembly of α-β isoforms has been less clear. We studied the effect of three β subunits on the cardiac α2 isoform and could show that β2 and β3 subunits greatly reduce K-affinity and show greater selectivity towards cardiotonic steroids. These findings help to understand the role of Na,K-ATPase in cardiac physiology and offer potential pharmaceutical applications.

Abstract: The genetic diversity of a species is the sum of the diversity found in all individuals of that species. One way to estimate the diversity of species is by resequencing diverse accessions and aligning the reads to a reference genome. While this approach readily identifies SNPs and small indels with respect to a reference genome, it underestimates total genomic diversity contained within a species because highly divergent regions align poorly to the reference and any sequence not found in the reference will be missed entirely. There is a considerable amount of structural variation including copy number variants (CNVs) and presence/absence variants (PAVs), which alter the total amount of genomic sequence found in individuals. Thus, the true extent of diversity within a plant species is largely unknown. De novo genome assemblies and annotation can be used to more accurately estimate the true genomic diversity within a species. Pan-genomes in other plant species have been created before but at a smaller scale. Previous studies used around 50 genomes to create the pan-genome. Here we present one of the largest studies with more than a thousand genotypes of Populus trichocarpa. We applied both approaches of reference-based alignment, as well as de novo assembly of unmapped reads, to create a pan-genome that contains all the diversity found in the accessions sequenced. Analysis of this data yielded a high-confidence Populus trichocarpa pan-genome that includes more 20,000 additional gene models relative to the reference. We have also used RNA Sequencing for generating expression profiles of individual accessions, with ca. 75% of the new gene models having expression evidence. We have used this RNA-Seq data to generate the pan-transcriptome profile of Populus trichocarpa and have identified new splice-site variants, found alternate exon-intron structures within the reference gene models and promoted alternate splice-site variants as the primary gene model.