Properties of the C-terminal domain of 4.1 proteins

Eur J Biochem. 2001 Jul;268(13):3709-17. doi: 10.1046/j.1432-1327.2001.02276.x.

Abstract

At the C-terminus of all known 4.1 proteins is a sequence domain unique to these proteins, known as the C-terminal domain (CTD). Mammalian CTDs are associated with a growing number of protein-protein interactions, although such activities have yet to be associated with invertebrate CTDs. Mammalian CTDs are generally defined by sequence alignment as encoded by exons 18-21. Comparison of known vertebrate 4.1 proteins with invertebrate (Caenorhabditis elegans and Drosophila melanogaster) 4.1 proteins indicates that mammalian 4.1 exon 19 represents a vertebrate adaptation that extends the sequence of the CTD with a Ser/Thr-rich sequence. The CTD was first described as a 22/24-kDa domain by chymotryptic digestion of erythrocyte 4.1 (4.1R) [Leto, T.L. & Marchesi, V.T. (1984) J. Biol. Chem. 259, 4603-4608]. Here we show that in 4.1R the 22/24-kDa fragment is not stable but rapidly processed to a 15-kDa fragment by chymotrypsin. The 15-kDa fragment is extremely stable, being resistant to overnight digestion in chymotrypsin on ice. Analysis of this fragment indicates that it is derived from residues 709-858 (SwissProt accession no. P48193), and represents the CTD of 4.1R. The fragment behaves as a globular monomer in solution. Secondary-structure predictions indicate that this domain is composed of five or six beta strands with an alpha helix before the most C-terminal of these. Together these data indicate that the CTD probably represents an independent folding structure which has gained function since the divergence of vertebrates from invertebrates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Caenorhabditis elegans / genetics
  • Chromatography, High Pressure Liquid
  • Chymotrypsin
  • Cytoskeletal Proteins / chemistry*
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism
  • Databases, Factual
  • Drosophila melanogaster / genetics
  • Erythrocytes / chemistry
  • Exons
  • Humans
  • Invertebrates
  • Mammals
  • Mass Spectrometry
  • Membrane Proteins / chemistry*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Molecular Sequence Data
  • Neuropeptides*
  • Peptide Fragments / chemistry
  • Sequence Alignment
  • Sequence Analysis, Protein
  • Sequence Homology, Amino Acid
  • Software

Substances

  • Cytoskeletal Proteins
  • Membrane Proteins
  • Neuropeptides
  • Peptide Fragments
  • erythrocyte membrane band 4.1 protein
  • erythrocyte membrane protein band 4.1-like 1
  • Chymotrypsin