PMID- 8322889
OWN - NLM
STAT- MEDLINE
DCOM- 19930805
LR  - 20171213
IS  - 0002-9513 (Print)
IS  - 0002-9513 (Linking)
VI  - 264
IP  - 6 Pt 2
DP  - 1993 Jun
TI  - Biosynthesis of the gp330/44-kDa Heymann nephritis antigenic complex: assembly 
      takes place in the ER.
PG  - F1011-20
AB  - The Heymann nephritis antigenic complex (HNAC) consists of two components, i.e., 
      1) gp330, a large glycoprotein localized in coated pits of the proximal tubule 
      and glomerular epithelium, and 2) a 44-kDa protein which is homologous to the 
      human alpha 2-macroglobulin receptor-associated protein (RAP). To examine the 
      biosynthesis and assembly of HNAC, tissue fragments prepared from 
      collagenase-digested 1-day-old rat kidneys were radiolabeled, and gp330 and RAP 
      were immunoprecipitated with specific antibodies. By electron microscopy the 
      tubule organization was seen to be largely intact. Results obtained on the 
      biosynthesis of a control brush border protein, dipeptidylpeptidase IV (DPPIV), 
      showed that tubules prepared in this manner are capable of synthesis and 
      posttranslational processing of brush border membrane proteins and thus are 
      suitable for short-term (< 3 h) biosynthetic experiments in vitro. Results of 
      pulse chase and digestion with endoglycosidase H (Endo H) indicated that the time 
      required for newly synthesized gp330 to mature in the endoplasmic reticulum (ER) 
      and transit the middle Golgi compartments [half time (t1/2) = 90 min] was 
      significantly longer than that of DPPIV (t1/2 = 20 min). Coprecipitation and 
      cosedimentation (sucrose velocity gradient centrifugation) experiments showed 
      that gp330 associates with RAP very early after synthesis and that the 44-kDa 
      protein remains associated with gp330 during its subsequent folding, 
      oligomerization, and transport to the Golgi. These findings demonstrate that HNAC 
      assembles in at least two steps. The first step is the association of gp330 with 
      RAP forming a large (19.3S) heterodimer, which sediments with the thyroglobulin 
      (mol wt = 669,000) standard. This step begins within 30 min of synthesis and is 
      Ca2+ dependent. The second step, which occurs > 60 min after synthesis, is the 
      formation of a larger heterooligomer, which results in a shift in size of the 
      complex from 19.3 to 38.6S. Both steps occur before acquisition of Endo H 
      resistance. These results indicate that HNAC consists of a large multimeric 
      complex that is assembled in the rough ER.
FAU - Biemesderfer, D
AU  - Biemesderfer D
AD  - Department of Medicine, Yale University School of Medicine, New Haven, 
      Connecticut 06510-3289.
FAU - Dekan, G
AU  - Dekan G
FAU - Aronson, P S
AU  - Aronson PS
FAU - Farquhar, M G
AU  - Farquhar MG
LA  - eng
GR  - DK-17724/DK/NIDDK NIH HHS/United States
GR  - DK-33793/DK/NIDDK NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Am J Physiol
JT  - The American journal of physiology
JID - 0370511
RN  - 0 (Heymann Nephritis Antigenic Complex)
RN  - 0 (Membrane Glycoproteins)
RN  - EC 3.2.1.96 (Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Animals, Newborn/metabolism
MH  - Biological Transport
MH  - Calcium/physiology
MH  - Drug Resistance
MH  - Endoplasmic Reticulum/*metabolism
MH  - Golgi Apparatus/metabolism
MH  - Heymann Nephritis Antigenic Complex
MH  - Intracellular Membranes/metabolism
MH  - Kidney/*metabolism
MH  - Kidney Glomerulus/immunology
MH  - Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase/pharmacology
MH  - Membrane Glycoproteins/*biosynthesis/chemistry
MH  - Molecular Weight
MH  - Rats
EDAT- 1993/06/01 00:00
MHDA- 1993/06/01 00:01
CRDT- 1993/06/01 00:00
PHST- 1993/06/01 00:00 [pubmed]
PHST- 1993/06/01 00:01 [medline]
PHST- 1993/06/01 00:00 [entrez]
AID - 10.1152/ajprenal.1993.264.6.F1011 [doi]
PST - ppublish
SO  - Am J Physiol. 1993 Jun;264(6 Pt 2):F1011-20. doi: 
      10.1152/ajprenal.1993.264.6.F1011.