Protein tyrosine kinase that is part of several cell surface receptor complexes, but that apparently needs a coreceptor for ligand binding. Essential component of a neuregulin-receptor complex, although neuregulins do not interact with it alone. GP30 is a potential ligand for this receptor. Regulates outgrowth and stabilization of peripheral microtubules (MTs). Upon ERBB2 activation, the MEMO1-RHOA-DIAPH1 signaling pathway elicits the phosphorylation and thus the inhibition of GSK3B at cell membrane. This prevents the phosphorylation of APC and CLASP2, allowing its association with the cell membrane. In turn, membrane-bound APC allows the localization of MACF1 to the cell membrane, which is required for microtubule capture and stabilization. In the nucleus is involved in transcriptional regulation. Associates with the 5'-TCAAATTC-3' sequence in the PTGS2/COX-2 promoter and activates its transcription. Implicated in transcriptional activation of CDKN1A; the function involves STAT3 and SRC. Involved in the transcription of rRNA genes by RNA Pol I and enhances protein synthesis and cell growth. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Activated by dimerization. Not activated by EGF, TGF-alpha and amphiregulin. Interaction with PTK6 increases its intrinsic kinase activity. Homodimer (PubMed:21454582). Heterodimer with EGFR, ERBB3 and ERBB4 (PubMed:10358079, PubMed:15093539, PubMed:21190959, PubMed:16978839). Part of a complex with EGFR and either PIK3C2A or PIK3C2B. May interact with PIK3C2B when phosphorylated on Tyr-1196 (PubMed:10805725). Interacts with PLXNB1 (PubMed:15210733). Interacts (when phosphorylated on Tyr-1248) with MEMO1 (PubMed:15156151). Interacts with MUC1; the interaction is enhanced by heregulin (HRG) (PubMed:12939402). Interacts (when phosphorylated on Tyr-1139) with GRB7 (via SH2 domain) (PubMed:12975581). Interacts (when phosphorylated on Tyr-1248) with ERBIN (PubMed:12444095). Interacts with KPNB1, RANBP2, EEA1, CRM1 and CLTC (PubMed:16314522). Interacts with PTK6 (PubMed:18719096). Interacts with RPA194 and ACTB (PubMed:21555369). Interacts with PRKCABP, SRC and MYOC (By similarity). Interacts (preferentially with the tyrosine phosphorylated form) with CPNE3; this interaction occurs at the cell membrane and is increased in a growth factor heregulin-dependent manner (PubMed:20010870). Interacts with HSP90AA1 and HSP90AB1 in an ATP-dependent manner; the interaction suppresses ERBB2 kinase activity (PubMed:26517842). Interacts with SORL1; this interaction regulates ERBB2 subcellular distribution by promoting its recycling after internalization from endosomes back to the plasma membrane, hence stimulates ERBB2-mediated signaling (PubMed:31138794). Translocation to the nucleus requires endocytosis, probably endosomal sorting and is mediated by importin beta-1/KPNB1. Also detected in VPS35-positive endosome-to-TGN retrograde vesicles (PubMed:31138794). Expressed in a variety of tumor tissues including primary breast tumors and tumors from small bowel, esophagus, kidney and mouth. Autophosphorylated. Autophosphorylation occurs in trans, i.e. one subunit of the dimeric receptor phosphorylates tyrosine residues on the other subunit (Probable). Ligand-binding increases phosphorylation on tyrosine residues (PubMed:27134172, PubMed:33497358). Signaling via SEMA4C promotes phosphorylation at Tyr-1248 (PubMed:17554007). Dephosphorylated by PTPN12 (PubMed:27134172). There are four alleles due to the variations in positions 654 and 655. Allele B1 (Ile-654/Ile-655) has a frequency of 0.782; allele B2 (Ile-654/Val-655) has a frequency of 0.206; allele B3 (Val-654/Val-655) has a frequency of 0.012. The gene represented in this entry is involved in disease pathogenesis. The gene represented in this entry is involved in disease pathogenesis. The gene represented in this entry is involved in disease pathogenesis. The protein represented in this entry is involved in disease pathogenesis. Chromosomal aberrations involving ERBB2 may be a cause gastric cancer. Deletions within 17q12 region producing fusion transcripts with CDK12, leading to CDK12-ERBB2 fusion leading to truncated CDK12 protein not in-frame with ERBB2. The disease is caused by variants affecting the gene represented in this entry. Produced by alternative initiation at Met-611 of isoform 1. Produced by alternative initiation at Met-687 of isoform 1. Produced by alternative splicing of isoform 1. Belongs to the protein kinase superfamily. Tyr protein kinase family. EGF receptor subfamily. ERBB2 entry