There are three sorCS genes that have diverse, partially overlapping functions in the central nervous system. In the developing and mature central nervous system, the homologous SorCS1 and SorCS2 genes and the SorCS3 gene are expressed in a combinatorial, non-overlapping pattern. SorCS proteins show homology to the mosaic receptor SorLA and the neurotensin receptor sortilin, based on a common VPS10 domain, which is the hallmark of the SorCS receptor family. SorCS1 is a type 1 receptor containing a VPS10P domain and a leucine-rich domain. Alternative splicing of human SorCS1 results in four isoforms with different cytoplasmic tails and differential expression in tissues. Human SorCS1 is detected in fetal and infant brain and in fetal retina. Alternative splicing of murine SorCS1 also results in four isoforms. Murine isoform 1 is highly expressed in brain and at lower levels in heart, liver and kidney. It is detected in newborn mouse brain and in adult olfactory bulb and cerebral cortex. Murine isoform 2 is highly expressed in liver and at lower levels in heart, brain, kidney and testis.