title: Structural studies on a 75-kDa glycoprotein isolated from porcine gastric mucosal membranes: close homology with the 78-kDa glucose-regulated family of proteins.
abstract: A 75-kDa glycoprotein (P75) has been purified to homogeneity from washed membranes isolated from the corpus of porcine gastric mucosa. The purification procedure employed chromatography on concanavalin A-Sepharose and DEAE-Sepharose, and preparative polyacrylamide gel electrophoresis. Reversed-phase microbore high-performance liquid chromatography was employed to fractionate and purify a number of tryptic peptides generated from approximately 1100 pmol purified P75. The use of reversed-phase microbore (2.1 mm internal diameter) columns facilitated the purification of subnanomole amounts of polypeptides in small volumes (40-60 microliter) suitable for loading onto the gas-phase sequencer without further concentration. N-Terminal amino acid sequence analyses were performed on the intact polypeptide and on 13 tryptic peptides and one Staphylococcus protease V8 peptide, yielding 170 unique assignments; this corresponds to approximately 26% of the molecule. A comparison of this amino acid sequence information with the cDNA-deduced primary structure of a 70-kDa heat-shock-related protein (P72), which is expressed in normal rat liver reveals that these protein sequences are almost identical, differing in only 1 of the 170 positions positively assigned thus far. The probable correspondence of P72 with the 78-kDa glucose-regulated protein (GRP78) isolated from hamster fibroblasts has been reported.
authors.affiliation: Ludwig Institute for Cancer Research, Melbourne Tumour Biology Branch, Parkville, Victoria, Australia.
authors.forename: G S
authors.initials: GS
authors.lastname: Baldwin
authors.forename: R
authors.initials: R
authors.lastname: Chandler
authors.forename: K L
authors.initials: KL
authors.lastname: Seet
authors.forename: J
authors.initials: J
authors.lastname: Weinstock
authors.forename: B
authors.initials: B
authors.lastname: Grego
authors.forename: M
authors.initials: M
authors.lastname: Rubira
authors.forename: R L
authors.initials: RL
authors.lastname: Mortiz
authors.forename: R J
authors.initials: RJ
authors.lastname: Simpson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005753:Gastric Mucosa / Q000032:analysis*; D006023:Glycoproteins / Q000302:isolation & purification; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins / Q000302:isolation & purification; D008969:Molecular Sequence Data; D013552:Swine
chemical_list: D006023:Glycoproteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; C018551:glucose-regulated proteins