10         20         30         40         50         60
         |          |          |          |          |          |
MEDLDQSPLV SSSDSPPRPQ PAFKYQFVRE PEDEEEEEEE EEEDEDEDLE ELEVLERKPA - 60
AGLSAAPVPT APAAGAPLMD FGNDFVPPAP RGPLPAAPPV APERQPSWDP SPVSSTVPAP - 120
SPLSAAAVSP SKLPEDDEPP ARPPPPPPAS VSPQAEPVWT PPAPAPAAPP STPAAPKRRG - 180
SSGSVVVDLL YWRDIKKTGV VFGASLFLLL SLTVFSIVSV TAYIALALLS VTISFRIYKG - 240
VIQAIQKSDE GHPFRAYLES EVAISEELVQ KYSNSALGHV NCTIKELRRL FLVDDLVDSL - 300
KFAVLMWVFT YVGALFNGLT LLILALISLF SVPVIYERHQ AQIDHYLGLA NKNVKDAMAK - 360
IQAKIPGLKR KAE

Nogo-B is one of three different isoforms (others including Nogo-A and -C) that are all generated from the gene RTN4, which is located on human chromosome 2, location p14-p13, by means of either alternative promoter usage and/or splicing. The N-terminus of Nogo-B is almost completely homologous to the first 200 residues of Nogo-A and has been determined to play a part in many integral biological processes, including interaction with beta-amyloid converting enzyme (BACE1), regulation of vascular remodeling, and induction of apoptosis. It is also believed that Nogo-B plays a role as a positive regulator of EC functions and as a negative regulator of SMC migration. The importance of Nogo molecules in general being intrinsically unstructured appears to serve two functional purposes for the organism, including generating/maintaining structures associated with the membrane as well as playing a role in such cellular signaling processes which are utilized in apoptosis, CNS neuronal regeneration, vascular remodeling, etc. The majority of the RTN4/Nogo molecules are concentrated in the ER with small amounts found on the cell surface. This protein is a potent neurite growth inhibitor in vitro and plays a role both in the restriction of axonal regeneration after injury and in structural plasticity in the CNS. Isoform 2 reduces the anti-apoptotic activity of Bcl-xl and Bcl-2. This is likely consecutive to their change in subcellular location, from the mitochondria to the endoplasmic reticulum, after binding and sequestration. Isoform 2 and isoform 3 inhibit BACE1 activity and amyloid precursor protein processing.