Isolation and characterization of three distinct 34 kDa EDTA-extractable proteins from bovine lens.
EDTA-extractable protein (EEP) is known to be a major lens membrane protein with a molecular mass in the range 32 kDa to 38 kDa, and is also known to bind to the lens membrane and phospholipid-containing liposomes in a calcium-dependent manner. Recent results (Russell, P., Zelenka, P., Martensen, J., and Reid, T.W. (1977) Curr. Eye Res. 6, 533-538) on antibody cross-reactivity have demonstrated that a 34-35 kDa component of EEP is identical to calpactin I (lipocortin II). In this study, we have identified and purified three distinct 34 kDa components of EEP (designated as EEP-34A1, EEP-34A2 and EEP-34B) from bovine lens that inhibit phospholipase A2 activity. These proteins bind to phospholipid-containing liposome and F-actin in a calcium-dependent fashion. Two-dimensional electrophoresis demonstrates that the three proteins were distinct from one another. However, immunochemical studies and one-dimensional peptide mapping indicate that EEP-34A1 and EEP-34B are very similar. Our results also indicate that EEP-34A1 is very similar to calpactin II and that EEP-34A2 corresponds to calpactin I. The bovine lens 34-35 kDa component of EEP is a mixture of proteins rather than a single protein.
Kobayashi
R
R
Department of Biochemistry, Akita University School of Medicine, Japan.
Tashima
Y
Y
Ohta
A
A
Nakayama
R
R
Ohsaka
Y
Y
Itoh
H
H
Wakizaka
A
A
Sakai
F
F
Sakuragi
S
S
D000199:Actins / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D017302:Annexins; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000032:analysis; D002417:Cattle; D002850:Chromatography, Gel; D003429:Cross Reactions; D003459:Crystallins / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification*; D004492:Edetic Acid / Q000494:pharmacology*; D015180:Electrophoresis, Gel, Two-Dimensional; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D054467:Phospholipases A2; D010743:Phospholipids / Q000378:metabolism
D000199:Actins; D000596:Amino Acids; D017302:Annexins; D002135:Calcium-Binding Proteins; D003459:Crystallins; D010743:Phospholipids; D004492:Edetic Acid; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium