Car11, also known as carbonic anhydrase-related protein XI (CA-RP XI), is a member of the alpha-carbonic anhydrase gene family. Although it lacks the typical catalytic activity of carbonic anhydrases due to inactivating changes in active-site residues, it likely has an important biological function. It may be involved in intracellular signal transduction as its amino-and carboxy-terminal regions have potential phosphorylation sites and binding motifs [5].

Transcriptional profiling detected Car11 expression in the neonatal mouse uterus between Postnatal Days 3 and 18, where its mRNA was predominantly localized in endometrial stromal cells [1]. In studies of Alzheimer's disease-related mouse models (5XFAD and T2KO mice), differential transcript usage (DTU) in Car11 was observed in neuronal and glial subtypes compared to wild-type mice, highlighting its potential role in the pathophysiology of Alzheimer's disease [2]. Phylogenetic analysis showed that the duplication of CA10 into Car11 occurred only in tetrapods. Immunohistochemical analysis and real-time quantitative PCR in mice indicated a wide distribution of Car11 mRNA, with positive signals in the cerebellum, cerebrum, liver, stomach, small intestine, colon, kidney, and testis [3]. During mammalian inner ear development, Car11 transcripts were expressed at higher levels, suggesting a role in inner ear development and function [4]. In murine embryonic studies, Car11 message was seen at an early gestational stage and expressed to a lesser extent as gestation progressed, and it was expressed in neuroprogenitor cells in the subventricular area and neural cells migrating to the cortex, suggesting an important role in the central nervous system (CNS) [6].

In conclusion, Car11 has a wide tissue distribution and is involved in multiple biological processes such as uterine development, inner ear development, and potentially in the pathophysiology of Alzheimer's disease and in CNS development. The use of mouse models in these studies has been crucial in uncovering these roles, providing insights into its functions and implications in various biological and disease-related contexts.