Monoclonal antibodies to dog heart sarcoplasmic reticulum as markers of endoplasmic reticulum.
A monoclonal antibody (mAb 4B4) was raised against purified sarcoplasmic reticulum vesicles from canine myocardium, and shown to inhibit Ca2+ uptake by microsomes isolated from cardiac, skeletal, and smooth muscle. The amount of mAb 4B4 needed to inhibit the Ca2+ uptake 50% at a given membrane concentration correlated with the amount of Ca2+ pump protein in the microsomal preparation. This is consistent with the observation the mAb 4B4 binds specifically to the sarcoplasmic/endoplasmic reticulum Ca2+ pump (Mr 100 kDa), but has no effect on the T-tubule Mg2+-ATPase. Changes in the binding of mAb 4B4 to crude microsomes isolated from dog heart after various durations of global ischemia showed that the decrease in microsomal Ca2+ transport during the first 15 min of ischemia correlated with a loss of active Ca2+ pump molecules. The monoclonal antibody mAb 4B4 may therefore serve as a specific marker for the sarcoplasmic/endoplasmic reticulum Ca2+ pump system in various cells, and can provide quantitative information about the loss of active Ca2+ pump proteins under pathological conditions.
Levitsky
D O
DO
Institute of Experimental Cardiology, Academy of Medical Sciences, Moscow, USSR.
Benevolensky
D S
DS
Ikemoto
N
N
Syrbu
S I
SI
Watras
J
J
D000818:Animals; D000911:Antibodies, Monoclonal; D015220:Calcium Channels / Q000276:immunology / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000276:immunology / Q000378:metabolism; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000276:immunology / Q000378:metabolism; D009206:Myocardium / Q000276:immunology* / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000276:immunology* / Q000378:metabolism
D000911:Antibodies, Monoclonal; D015220:Calcium Channels; D000252:Calcium-Transporting ATPases