Among the about 20,000 genes in the human proteome there are still many rather unknown but potentially interesting proteins that could deserve some extra attention. Here we will focus on SBK2, a gene specifically expressed in the heart.

The heart is one of our most important organs and the engine of the human circulatory system. It is a fist-sized muscular organ pumping blood through our blood vessels while supplying oxygen and nutrient-rich blood to tissues and organs and removing waste products like carbon dioxide. Transcriptome analysis shows that 68% of all human proteins are expressed in this important organ system with almost 200 genes showing enriched expression in the heart compared to other tissue types.

Many of the heart enriched genes are well-known with known functions, but among them we also find SBK2, a rather unknown gene with neither known function nor protein evidence in the UniProt database. That this 'Gene Doe' has a function related to the heart is however strongly suggested by the expression profile in both bulk and single cell RNA seq which show enrichment in heart muscle and more specifically cardiomyocytes. Expression clustering and correlation of tissue and single cell RNA seq data further show SBK2 to cluster together with other genes known to be related to heart development and cardiomyocytes. Immunohistochemical staining of the protein confirms these findings by showing specific expression in cardiomyocytes.