Protein: Agrin [Cleaved into: Agrin N-terminal 110 kDa subunit; Agrin C-terminal 110 kDa subunit; Agrin C-terminal 90 kDa fragment (C90); Agrin C-terminal 22 kDa fragment (C22)] (P25304)
Organism: Rattus norvegicus (Rat)
Function: Heparan sulfate basal lamina glycoprotein that plays a central role in the formation and the maintenance of the neuromuscular junction (NMJ) and directs key events in postsynaptic differentiation. This neuron-specific (z+) isoform is a component of the AGRN-LRP4 receptor complex that induces the phosphorylation and activation of MUSK. The activation of MUSK in myotubes induces the formation of NMJ by regulating different processes including the transcription of specific genes and the clustering of AChR in the postsynaptic membrane. Calcium ions are required for maximal AChR clustering. AGRN function in neurons is highly regulated by alternative splicing, glycan binding and proteolytic processing. Modulates calcium ion homeostasis in neurons, specifically by inducing an increase in cytoplasmic calcium ions. Functions differentially in the central nervous system (CNS) by inhibiting the alpha(3)-subtype of Na+/K+-ATPase and evoking depolarization at CNS synapses. This transmembrane agrin (TM-agrin) isoform, the predominate form in neurons of the brain, induces dendritic filopodia and synapse formation in mature hippocampal neurons in large part due to the attached glycosaminoglycan chains and the action of Rho-family GTPases.
Subcellular location: Synapse {ECO:0000269|PubMed:8653787}. Cell membrane {ECO:0000269|PubMed:11161480}; Single-pass type II membrane protein {ECO:0000269|PubMed:11161480}.
Interaction partners:
- Low-density lipoprotein receptor-related protein 4
- Dystroglycan 1
- Muscle, skeletal receptor tyrosine protein kinase
- Docking protein 7
- Nidogen-1
- Neuronal acetylcholine receptor subunit alpha-2
- 43 kDa receptor-associated protein of the synapse
- Biglycan
- Basement membrane-specific heparan sulfate proteoglycan core protein
- Dystrophin
Sequence:
MPPLPLEHRPRQEPGASMLVRYFMIPCNICLILLATSTLGFAVLLFLSNYKPGIHFTPAPPTPPDVCRGMLCGFGAVCEPSVEDPGRASCVCKKNACPATVAPVCGSDASTYSNECELQRAQCNQQRRIRLLRQGPCGSRDPCANVTCSFGSTCVPSADGQTASCLCPTTCFGAPDGTVCGSDGVDYPSECQLLSHACASQEHIFKKFNGPCDPCQGSMSDLNHICRVNPRTRHPEMLLRPENCPAQHTPICGDDGVTYENDCVMSRIGATRGLLLQKVRSGQCQTRDQCPETCQFNSVCLSRRGRPHCSCDRVTCDGSYRPVCAQDGHTYNNDCWRQQAECRQQRAIPPKHQGPCDQTPSPCHGVQCAFGAVCTVKNGKAECECQRVCSGIYDPVCGSDGVTYGSVCELESMACTLGREIQVARRGPCDPCGQCRFGSLCEVETGRCVCPSECVESAQPVCGSDGHTYASECELHVHACTHQISLYVASAGHCQTCGEKVCTFGAVCSAGQCVCPRCEHPPPGPVCGSDGVTYLSACELREAACQQQVQIEEAHAGPCEPAECGSGGSGSGEDDECEQELCRQRGGIWDEDSEDGPCVCDFSCQSVPRSPVCGSDGVTYGTECDLKKARCESQQELYVAAQGACRGPTLAPLLPVAFPHCAQTPYGCCQDNFTAAQGVGLAGCPSTCHCNPHGSYSGTCDPATGQCSCRPGVGGLRCDRCEPGFWNFRGIVTDGHSGCTPCSCDPRGAVRDDCEQMTGLCSCRPGVAGPKCGQCPDGQVLGHLGCEADPMTPVTCVEIHCEFGASCVEKAGFAQCICPTLTCPEANSTKVCGSDGVTYGNECQLKAIACRQRLDISTQSLGPCQESVTPGASPTSASMTTPRHILSKTLPFPHNSLPLSPGSTTHDWPTPLPISPHTTVSIPRSTAWPVLTVPPTAAASDVTSLATSIFSESGSANGSGDEELSGDEEASGGGSGGLEPPVGSIVVTHGPPIERASCYNSPLGCCSDGKTPSLDSEGSNCPATKAFQGVLELEGVEGQELFYTPEMADPKSELFGETARSIESTLDDLFRNSDVKKDFWSVRLRELGPGKLVRAIVDVHFDPTTAFQASDVGQALLRQIQVSRPWALAVRRPLQEHVRFLDFDWFPTFFTGAATGTTAAMATARATTVSRLPASSVTPRVYPSHTSRPVGRTTAPPTTRRPPTTATNMDRPRTPGHQQPSKSCDSQPCLHGGTCQDQDSGKGFTCSCTAGRGGSVCEKVQPPSMPAFKGHSFLAFPTLRAYHTLRLALEFRALETEGLLLYNGNARGKDFLALALLDGRVQFRFDTGSGPAVLTSLVPVEPGRWHRLELSRHWRQGTLSVDGETPVVGESPSGTDGLNLDTNLYVGGIPEEQVAMVLDRTSVGVGLKGCIRMLDINNQQLELSDWQRAAVQSSGVGECGDHPCLPNPCHGGALCQALEAGMFLCQCPPGRFGPTCADEKSPCQPNPCHGAAPCRVLSSGGAKCECPLGRSGTFCQTVLETAGSRPFLADFNGFSYLELKGLHTFERDLGEKMALEMVFLARGPSGLLLYNGQKTDGKGDFVSLALHNRHLEFCYDLGKGAAVIRSKEPIALGTWVRVFLERNGRKGALQVGDGPRVLGESPKSRKVPHTMLNLKEPLYIGGAPDFSKLARGAAVSSGFSGVIQLVSLRGHQLLTQEHVLRAVDVSPFADHPCTQALGNPCLNGGSCVPREATYECLCPGGFSGLHCEKGLVEKSVGDLETLAFDGRTYIEYLNAVIESELTNEIPAPETLDSRALFSEKALQSNHFELSLRTEATQGLVLWIGKAAERADYMALAIVDGHLQLSYDLGSQPVVLRSTVKVNTNRWLRIRAHREHREGSLQVGNEAPVTGSSPLGATQLDTDGALWLGGLQKLPVGQALPKAYGTGFVGCLRDVVVGHRQLHLLEDAVTKPELRPCPTP