Characterization of mammalian heart annexins with special reference to CaBP33 (annexin V).
Porcine heart was observed to express annexins V (CaBP33) and VI in large amounts, and annexins III and IV in much smaller amounts. Annexin V (CaBP33) in porcine heart was examined in detail by immunochemistry. Homogenization and further processing of heart in the presence of EGTA resulted in the recovery of annexin V (CaBP33) in the cytosolic fraction and in an EGTA-resistant, Triton X-100-soluble fraction from cardiac membranes. Including Ca2+ in the homogenization medium resulted in a significant decrease in the annexin V (CaBP33) content of the cytosolic fraction with concomitant increase in the content of this protein in myofibrils, mitochrondria, the sarcoplasmic reticulum and the sarcolemma. The amount of annexin V (CaBP33) in each of these subfractions depended on the free Ca2+ concentration in the homogenizing medium. At the lowest free Ca2+ concentration tested, 0.8 microM, only the sarcolemma appeared to contain bound annexin V (CaBP33). Membrane-bound annexins V (CaBP33) and VI partitioned in two fractions, one EGTA-resistant and Triton X-100-extractable, and one Triton X-100-resistant and EGTA-extractable. Altogether, these data suggest that annexins V and VI are involved in the regulation of membrane-related processes.
Pula
G
G
Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Italy.
Bianchi
R
R
Ceccarelli
P
P
Giambanco
I
I
Donato
R
R
D000818:Animals; D017304:Annexin A5; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000032:analysis* / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D008929:Mitochondria, Heart / Q000737:chemistry; D008970:Molecular Weight; D009206:Myocardium / Q000737:chemistry*; D010743:Phospholipids / Q000378:metabolism; D011257:Pregnancy Proteins / Q000032:analysis* / Q000378:metabolism; D012508:Sarcolemma / Q000737:chemistry; D012519:Sarcoplasmic Reticulum / Q000737:chemistry; D013552:Swine
D017304:Annexin A5; D002135:Calcium-Binding Proteins; D010743:Phospholipids; D011257:Pregnancy Proteins; D004533:Egtazic Acid