Neuron redundancy

Very low-density lipoprotein receptor ( VLDLR) and APOE receptor-2 ( APOER2) are two gene family members with redundant functions. They are expressed in neurons of the developing brain and act as cell... 

The second cell-specific regulatory element within the distal enhancer is named SER. Loss of this element, which is at the extreme distal edge of the enhancer, leads to a selective loss of DDC expression in the ventral lateral serotonin cells (Johnson et al., 1989 Lundell and Hirsh, 1992) (Fig. 6C). This element has been delimited to about 40 bp and shows unexpected complexity, consisting of two functionally redundant elements. These two subelements, SERl and SERr, are each sufficient to allow normal DDC expression in the ventral lateral serotonin neurons if the other is deleted. In spite of this functional similarity, no sequence similarity is apparent between the two regions. The region of conservation between D. melanogaster and D. virilis is limited to SERl. 

Todd, J.L., Haynes, K.F. and Baker, T. C. (1992). Antennal neurones specific for redundant pheromone components in normal and mutant Trichoplusia ni males. Physiological Entomology 17 183-192. 

Janz R, Goda Y, Geppert M, Missler M, Sudhof TC (1999) SV2A and SV2B function as redundant Ca2+ regulators in neurotransmitter release. Neuron 24 1003-1016. 

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