Epithelial integrin alpha 6 beta 4: complete primary structure of alpha 6 and variant forms of beta 4

J Cell Biol. 1990 Oct;111(4):1593-604. doi: 10.1083/jcb.111.4.1593.


The integrin alpha 6 beta 4 is a heterodimer predominantly expressed by epithelia. While no definite receptor function has yet been assigned to it, this integrin may mediate adhesive and/or migratory functions of epithelial cells. We have determined the complete primary structure of both the alpha 6 and beta 4 subunits from cDNA clones isolated from pancreatic carcinoma cell line libraries. The deduced amino acid sequence of alpha 6 is homologous to other integrin alpha chains (18-26% identity). Antibodies to an alpha 6 carboxy terminus peptide immunoprecipitated alpha 6 beta 4 complexes from carcinoma cells and alpha 6 beta 1 complexes from platelets, providing further evidence for the association of alpha 6 with more than one beta subunit. The deduced amino acid sequence of beta 4 predicts an extracellular portion homologous to other integrin beta chains, and a unique cytoplasmic domain comprised of greater than 1,000 residues. This agrees with the structures of the beta 4 cDNAs from normal epithelial cells (Suzuki, S., and Y. Naitoh. 1990. EMBO [Eur. Mol. Biol. Organ.] J. 9:757-763; Hogervost, F., I. Kuikman, A. E. G. Kr. von dem Borne, and A. Sonnenberg. 1990. EMBO [Eur. Mol. Biol. Organ.] J. 9:765-770). Compared to these structures, however, the beta 4 cDNAs that we have cloned from carcinoma cells contain extra sequences. One of these is located in the 5'-untranslated region, and may encode regulatory sequences. Another specifies a segment of 70 amino acids in the cytoplasmic tail. Amplification by reverse transcription-polymerase chain reaction of mRNA indicated that multiple forms of beta 4 may exist, possibly due to cell-type specific alternative splicing. The unique structure of beta 4 suggests its involvement in novel cytoskeletal interactions. Consistent with this possibility, alpha 6 beta 4 is mostly concentrated on the basal surface of epithelial cells, but does not colocalize with components of adhesion plaques.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cell Compartmentation
  • Cloning, Molecular
  • Fluorescent Antibody Technique
  • Humans
  • Integrins / chemistry*
  • Integrins / genetics*
  • Macromolecular Substances
  • Molecular Sequence Data
  • Poly A / analysis
  • Polymerase Chain Reaction
  • RNA, Messenger / analysis
  • Sequence Alignment
  • Sequence Homology, Nucleic Acid


  • Integrins
  • Macromolecular Substances
  • RNA, Messenger
  • Poly A

Associated data

  • GENBANK/X53586
  • GENBANK/X53587