small regulatory polypeptide of amino acid response (SPAAR, LINC00961, SPAR)

Function

• isoform 2: negative regulator of amino acid sensing & mTORC1, a signaling complex promoting cell growth in response to growth factors, energy levels & amino acids
• negatively regulates mTORC1 activation by inhibiting recruitment of mTORC1 to lysosomes upon stimulation with amino acids
• acts by promoting formation of a tightly bound supercomplex composed of the lysosomal V-ATPase, Ragulator & Rag GTPases, preventing recruitment of mTORC1
• acts as a regulator of muscle regeneration following injury by regulating mTORC1 activation (putative)
• interacts with components of the lysosomal V-ATPase complex
• interacts with ATP6V0A1 & ATP6V0A2

Compartment

• single-pass membrane protein
• late endosome membrane, lysosome membrane

Alternative initiation

named isoforms=2

Expression

• highly expressed in lung, heart & skeletal muscle

More general terms

• membrane protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=158376
• UniProt: http://www.uniprot.org/uniprot/A0A1B0GVQ0.html