Nav1.5 kb. The gene consists of 28 exons, of which exon 1 and in part exon 2 form the 5’ untranslated region (5’UTR) and exon 28 the 3’ untranslated region (3’UTR) of the RNA. SCN5A is part of a family of 10 genes that encode different types of sodium channels, i.e. brain-type (Na1.1, Na1.2, Na1.3, Na1.6), neuronal channels (Na1.7, Na1.8 and Na1.9), skeletal muscle channels (Na1.4) and the cardiac sodium channel Na1.5. SCN5A is mainly expressed in the heart, where expression is abundant in working myocardium and conduction tissue. In contrast, expression is low in the sinoatrial node and atrioventricular node.
Lymph node stromal cell travel from the bone marrow or high endothelial venules of the thymus where they develop as lymphoblasts, to lymph nodes, where they mature. The primary role of lymph node stromal cells is structural. They form a scaffold for hematopoietic cells and assist their movement along it. The molecular signaling systems (chemokines) that distribute lymphocytes to appropriate localities within the lymph node (T and B cell segregation) are also created by lymph node stromal cells. Lymphocytes have receptors for such chemokines. For example, Naive T cells express the CCR7 receptor for the chemokine CCL21. and B cells exhibit CXCR5 receptors for