Macrosialin, a mouse macrophage-restricted glycoprotein, is a member of the lamp/lgp family

J Biol Chem. 1993 May 5;268(13):9661-6.


Macrosialin is a heavily glycosylated transmembrane protein of 87-115 kDa, highly and specifically expressed by mouse tissue macrophages, and to a lesser extent by dendritic cells. We have isolated cDNA clones encoding macrosialin from a thioglycollate-elicited peritoneal macrophage cDNA library by transient expression in COS cells and panning with the anti-macrosialin monoclonal antibody FA/11. A single 1.3-kilobase macrosialin transcript was detected in both untreated and phorbol 12-myristate 13-acetate-stimulated RAW cells. The cDNA sequence predicts a type I integral membrane protein of 326 residues with a heavily glycosylated extracellular domain of 306 residues containing nine potential N-linked glycosylation sites and numerous potential O-linked glycosylation sites. The extracellular domain consists of two distinct regions, separated by an extended 12 residue proline-rich hinge; a membrane-distal mucin-like domain of 89 residues containing short peptide repeats and consisting of 44% serine and threonine residues; and a membrane proximal domain of 170 residues, which has significant sequence homology to a family of lysosomal associated glycoproteins known as the lamp-1 group. Macrosialin is the murine homologue of the human macrophage glycoprotein CD68 (72% identity, 80% similarity). Both proteins are preferentially expressed by macrophages and share the same bipartite structure having a mucin-like domain and a domain common to the lamp family. Macrosialin and CD68 are the first examples of a lamp family protein with a restricted cell-type-specific expression. They may have evolved from the lamps to carry out specialized functions in dedicated phagocytic cells.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, CD / genetics
  • Antigens, Differentiation, Myelomonocytic / genetics
  • Base Sequence
  • Blotting, Northern
  • Cell Line
  • Cells, Cultured
  • Cloning, Molecular
  • DNA / genetics*
  • Gene Library
  • Humans
  • Lysosomal Membrane Proteins
  • Macrophages / drug effects
  • Macrophages / metabolism*
  • Membrane Glycoproteins / biosynthesis
  • Membrane Glycoproteins / chemistry
  • Membrane Glycoproteins / genetics*
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Oligodeoxyribonucleotides
  • Plasmids
  • Polymerase Chain Reaction / methods
  • Protein Conformation
  • RNA, Messenger / analysis
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Sequence Homology, Amino Acid
  • Tetradecanoylphorbol Acetate / pharmacology
  • Transfection


  • Antigens, CD
  • Antigens, Differentiation, Myelomonocytic
  • CD68 antigen, human
  • CD68 protein, mouse
  • Lysosomal Membrane Proteins
  • Membrane Glycoproteins
  • Oligodeoxyribonucleotides
  • RNA, Messenger
  • DNA
  • Tetradecanoylphorbol Acetate

Associated data

  • GENBANK/X68273