The following text describes a protein:
Function:
Membrane-bound mucin, a family of highly glycosylated proteins that constitute the major component of the mucus, the slimy and viscous secretion covering epithelial surfaces. These glycoproteins play important roles in the protection of the epithelium and are implicated in epithelial renewal and differentiation. Regulates cellular behavior through both anti-adhesive effects on cell-cell and cell-extracellular matrix interactions and its ability to act as an intramembrane ligand for ERBB2. Plays an important role in proliferation and differentiation of epithelial cells by inducing specific phosphorylation of ERBB2. In polarized epithelial cells, segregates ERBB2 and other ERBB receptors and prevents ERBB2 from acting as a coreceptor. The interaction with ERBB2 leads to enhanced expression of CDKN1B. The formation of a MUC4-ERBB2-ERBB3-NRG1 complex leads to down-regulation of CDKN1B, resulting in repression of apoptosis and stimulation of proliferation. Its ability to promote tumor growth may be mainly due to repression of apoptosis as opposed to proliferation.
Miscellaneous:
MISCELLANEOUS: Expression is a very useful predictor of poor prognosis in patients with invasive ductal carcinoma and intrahepatic cholangiocarcinoma, mass forming type (IDC,ICC-MF). Patients with IDC or ICC-MF who have high MUC4 expression had a worse survival rate than those with low MUC4 expression; MISCELLANEOUS: [Isoform 2]: May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay; MISCELLANEOUS: [Isoform 3]: May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay; MISCELLANEOUS: [Isoform 5]: May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay; MISCELLANEOUS: [Isoform 7]: May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay; MISCELLANEOUS: [Isoform 8]: May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay; MISCELLANEOUS: [Isoform 9]: Dubious isoform produced through aberrant splice sites; MISCELLANEOUS: [Isoform 11]: May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay; MISCELLANEOUS: [Isoform 12]: May be preferentially expressed in tumor tissues; MISCELLANEOUS: [Isoform 13]: May be preferentially expressed in tumor tissues; MISCELLANEOUS: [Isoform 15]: May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay; MISCELLANEOUS: [Isoform 16]: Dubious isoform produced through aberrant splice sites; MISCELLANEOUS: [Isoform 17]: Dubious isoform produced through aberrant splice sites.
Subcellular Localization:
[Mucin-4 beta chain]: Cell membrane; Single-pass membrane protein. Note=Isoforms lacking the Cys-rich region, EGF-like domains and transmembrane region are secreted. Secretion occurs by splicing or proteolytic processing; [Mucin-4 alpha chain]: Cell membrane. Secreted. Note=Forms a complex with Mucin-4 beta chain at the cell membrane; [Isoform 3]: Cell membrane; Single-pass membrane protein; [Isoform 11]: Secreted; [Isoform 15]: Secreted; [Isoform 17]: Cell membrane; Single-pass membrane protein.
Domain:
[Mucin-4 alpha chain]: Essentially composed of an array of serine- and threonine-rich tandem repeats which is highly polymorphic, the variable number of tandem repeats (VNTR) region.
Sequence:
MKGARWRRVPWVSLSCLCLCLLPHVVPGTTEDTLITGSKTAAPVTSTGSTTATLEGQSTAASSRTSNQDISASSQNHQTKSTETTSKAQTDTLTQMMTSTLFSSPSVHNVMETAPPDEMTTSFPSSVTNTLMMTSKTITMTTSTDSTLGNTEETSTAGTESSTPVTSAVSITAGQEGQSRTTSWRTSIQDTSASSQNHWTRSTQTTRESQTSTLTHRTTSTPSFSPSVHNVTGTVSQKTSPSGETATSSLCSVTNTSMMTSEKITVTTSTGSTLGNPGETSSVPVTGSLMPVTSAALVTFDPEGQSPATFSRTSTQDTTAFSKNHQTQSVETTRVSQINTLNTLTPVTTSTVLSSPSGFNPSGTVSQETFPSGETTTSSPSSVSNTFLVTSKVFRMPTSRDSTLGNTEETSLSVSGTISAITSKVSTIWWSDTLSTALSPSSLPPKISTAFHTQQSEGAETTGRPHERSSFSPGVSQEIFTLHETTTWPSSFSSKGHTTWSQTELPSTSTGAATRLVTGNPSTGTAGTIPRVPSKVSAIGEPGEPTTYSSHSTTLPKTTGAGAQTQWTQETGTTGEALLSSPSYSVTQMIKTATSPSSSPMLDRHTSQQITTAPSTNHSTIHSTSTSPQESPAVSQRGHTQAPQTTQESQTTRSVSPMTDTKTVTTPGSSFTASGHSPSEIVPQDAPTISAATTFAPAPTGDGHTTQAPTTALQAAPSSHDATLGPSGGTSLSKTGALTLANSVVSTPGGPEGQWTSASASTSPDTAAAMTHTHQAESTEASGQTQTSEPASSGSRTTSAGTATPSSSGASGTTPSGSEGISTSGETTRFSSNPSRDSHTTQSTTELLSASASHGAIPVSTGMASSIVPGTFHPTLSEASTAGRPTGQSSPTSPSASPQETAAISRMAQTQRTRTSRGSDTISLASQATDTFSTVPPTPPSITSTGLTSPQTETHTLSPSGSGKTFTTALISNATPLPVTYASSASTGHTTPLHVTDASSVSTGHATPLPVTSPSSVSTGHTTPLPVTDTSSESTGHVTPLPVTSFSSASTGDSTPLPVTDTSSASTGHVTPLPVTSLSSASTGDTTPLPVTDTSSASTGHATSLPVTDTSSVSTGHTTPLPVTDTSSASTGHATSLPVTDTSSVSTGHTTPLHVTDASSASTGQATPLPVTSLSSVSTGDTTPLPVTSPSSASTGHATPLLVTDTSSASTGHATPLPVTDASSVSTDHATSLPVTIPSAASTGHTTPLPVTDTSSASTGQATSLLVTDTSSVSTGDTTPLPVTSTSSASTGHVTPLHVTSPSSASTGHATPLPVTSLSSASTGDTMPLPVTSPSSASTGDTTPLPVTDASSVSTGHTTPLHVTDASSASTGQATPLPVTSLSSVSTGDTTPLPVTSPSSASTGHATPLLVTDTSSASTGHATPLPVTDASSVSTDHATSLPVTIPSAASTGHTTPLPVTDTSSASTGQATSLLVTDTSSVSTGDTTPLPVTSTSSASTGHVTPLHVTSPSSASTGHATPLPVTSLSSASTGDTMPLPVTSPSSASTGDTTPLPVTDASSVSTGHTTPLPVTSPSSASTGHTTPLPVTDTSSASKGDTTPLPVTSPSSASTGHTTPLPVTDTSSASTGDTTPLPVTNASSLSTGHATPLHVTSPSSASTGHATPLPVTSTSSASTGHATPLPVTGLSSATTDDTTRLPVTDVSSASTGQATPLPVTSLSSVSTGDTTPLPVTSPSSASTGHASPLLVTDASSASTGQATPLPVTDTSSVSTAHATPLPVTGLSSASTDDTTRLPVTDVSSASTGQAIPLPVTSPSSASTGDTTPLPVTDASSASTGDTTSLPVTIPSSASSGHTTSLPVTDASSVSTGHATSLLVTDASSVSTGDTTPLPVTDTNSASTGDTTPLHVTDASSVSTGHATSLPVTSLSSASTGDTTPLPVTSPSSASSGHTTPLPVTDASSVPTGHATSLPVTDASSVSTGHATPLPVTDASSVSTGHATPLPVTDTSSVSTGQATPLPVTSLSSASTGDTTPLPVTDTSSASTGQDTPLPVTSLSSVSTGDTTPLPVTNPSSASTGHATPLLVTDASSISTGHATSLLVTDASSVSTGHATALHDTDASSLSTGDTTPLPVTSPSSTSTGDTTPLPVTETSSVSTGHATSLPVTDTSSASTGHATSLPVTDTSSASTGHATPLPVTDTSSASTGQATPLPVTSPSSASTGHAIPLLVTDTSSASTGQATPLPVTSLSSASTGDTTPLPVTDASSVSTGHATSLPVTSLSSVSTGDTTPLPVTSPSSASTGHATPLHVTDASSASTGHATPLPVTSLSSASTGDTTPLPVTSPSSASTGHATPLHVTDASSVSTGDTTPLPVTSSSSASSGHTTPLPVTDASSASTGDTTPLPVTDTSSASTGHATHLPVTGLSSASTGDTTRLPVTNVSSASTGHATPLPVTSTSSASTGDTTPLPGTDTSSVSTGHTTPLLVTDASSVSTGDTTRLPVTSPSSASTGHTTPLPVTDTPSASTGDTTPLPVTNASSLSTRHATSLHVTSPSSASTGHATSLPVTDTSAASTGHATPLPVTSTSSASTGDTTPLPVTDTYSASTGQATPLPVTSLSSVSTGDTTPLPVTSPSSASTGHATPLLVTDASSASTGQATPLPVTSLSSVSTGDTTPLPVTSPSSASTGHATSLPVTDTSSASTGDTTSLPVTDTSSAYTGDTTSLPVTDTSSSSTGDTTPLLVTETSSVSTGDTTPLPVTDTSSASTGHATPLPVTNTSSVSTGHATPLHVTSPSSASTGHTTPLPVTDASSVSTGHATSLPVTDASSVFTGHATSLPVTIPSSASSGHTTPLPVTDASSVSTGHATSLPVTDASSVSTGHATPLPVTDASSVSTGHATPLPLTSLSSVSTGDTTPLPVTDTSSASTGQATPLPVTSLSSVSTGDTTPLPVTDTSSASTGHATSLPVTDTSSASTGHATPLPDTDTSSASTGHATLLPVTDTSSASIGHATSLPVTDTSSISTGHATPLHVTSPSSASTGHATPLPVTDTSSASTGHANPLHVTSPSSASTGHATPLPVTDTSSASTGHATPLPVTSLSSVSTGDTTPLPVTSPSSASTGHTTPLPVTDTSSASTGQATALPVTSTSSASTGDTTPLPVTDTSSASTGQATPLPVTSLSSVSTGDTTPLPVTSPSSASTGHATPLLVTDASSASTGQATPLPVTSLSSVSTGDTTPLPVTSPSSASTGHATSLPVTDTSSASTGDTTSLPVTDTSSAYTGDTTSLPVTDTSSSSTGDTTPLLVTETSSVSTGHATPLLVTDASSASTGHATPLHVTSPSSASTGDTTPVPVTDTSSVSTGHATPLPVTGLSSASTGDTTRLPVTDISSASTGQATPLPVTNTSSVSTGDTMPLPVTSPSSASTGHATPLPVTSTSSASTGHATPVPVTSTSSASTGHTTPLPVTDTSSASTGDTTPLPVTSPSSASTGHTTPLHVTIPSSASTGDTSTLPVTGASSASTGHATPLPVTDTSSVSTGHATPLPVTSLSSVSTGDTTPLPVTDASSASTGQATPLPVTSLSSVSTGDTTPLLVTDASSVSTGHATPLPVTDTSSASTGDTTRLPVTDTSSASTGQATPLPVTSLSSVSTGDTTPLLVTDASSVSTGHATPLPVTDTSSASTGDTTRLPVTDTSSASTGQATPLPVTIPSSSSSGHTTPLPVTSTSSVSTGHVTPLHVTSPSSASTGHVTPLPVTSTSSASTGHATPLLVTDASSVSTGHATPLPVTDASSASTGDTTPLPVTDTSSASTGQATPLPVTSLSSVSTGDTTPLPVTDASSASTGHATPLPVTIPSSVSTGDTMPLPVTSPSSASTGHATPLPVTGLSSASTGDTTPLPVTDTSSASTRHATPLPVTDTSSASTDDTTRLPVTDVSSASTGHATPLPVTSTSSASTGDTTPLPVTDTSSVSTGHATSLPVTSRSSASTGHATPLPVTDTSSVSTGHATPLPVTSTSSVSTGHATPLPVTSPSSASTGHATPVPVTSTSSASTGDTTPLPVTNASSLSTGHATPLHVTSPSSASRGDTSTLPVTDASSASTGHATPLPLTSLSSVSTGDTTPLPVTDTSSASTGQATPLPVTSLSSVSTGDTTPLPVTIPSSASSGHTTSLPVTDASSVSTGHGTPLPVTSTSSASTGDTTPLPVTDTSSASTGHATPLPVTDTSSASTGHATPLPVTSLSSVSTGHATPLAVSSATSASTVSSDSPLKMETPGMTTPSLKTDGGRRTATSPPPTTSQTIISTIPSTAMHTRSTAAPIPILPERGVSLFPYGAGAGDLEFVRRTVDFTSPLFKPATGFPLGSSLRDSLYFTDNGQIIFPESDYQIFSYPNPLPTGFTGRDPVALVAPFWDDADFSTGRGTTFYQEYETFYGEHSLLVQQAESWIRKMTNNGGYKARWALKVTWVNAHAYPAQWTLGSNTYQAILSTDGSRSYALFLYQSGGMQWDVAQRSGNPVLMGFSSGDGYFENSPLMSQPVWERYRPDRFLNSNSGLQGLQFYRLHREERPNYRLECLQWLKSQPRWPSWGWNQVSCPCSWQQGRRDLRFQPVSIGRWGLGSRQLCSFTSWRGGVCCSYGPWGEFREGWHVQRPWQLAQELEPQSWCCRWNDKPYLCALYQQRRPHVGCATYRPPQPAWMFGDPHITTLDGVSYTFNGLGDFLLVGAQDGNSSFLLQGRTAQTGSAQATNFIAFAAQYRSSSLGPVTVQWLLEPHDAIRVLLDNQTVTFQPDHEDGGGQETFNATGVLLSRNGSEVSASFDGWATVSVIALSNILHASASLPPEYQNRTEGLLGVWNNNPEDDFRMPNGSTIPPGSPEEMLFHFGMTWQINGTGLLGKRNDQLPSNFTPVFYSQLQKNSSWAEHLISNCDGDSSCIYDTLALRNASIGLHTREVSKNYEQANATLNQYPPSINGGRVIEAYKGQTTLIQYTSNAEDANFTLRDSCTDLELFENGTLLWTPKSLEPFTLEILARSAKIGLASALQPRTVVCHCNAESQCLYNQTSRVGNSSLEVAGCKCDGGTFGRYCEGSEDACEEPCFPSVHCVPGKGCEACPPNLTGDGRHCAALGSSFLCQNQSCPVNYCYNQGHCYISQTLGCQPMCTCPPAFTDSRCFLAGNNFSPTVNLELPLRVIQLLLSEEENASMAEVNASVAYRLGTLDMRAFLRNSQVERIDSAAPASGSPIQHWMVISEFQYRPRGPVIDFLNNQLLAAVVEAFLYHVPRRSEEPRNDVVFQPISGEDVRDVTALNVSTLKAYFRCDGYKGYDLVYSPQSGFTCVSPCSRGYCDHGGQCQHLPSGPRCSCVSFSIYTAWGEHCEHLSMKLDAFFGIFFGALGGLLLLGVGTFVVLRFWGCSGARFSYFLNSAEALP