Novel isoforms of CaBP 33/37 (annexin V) from mammalian brain: structural and phosphorylation differences that suggest distinct biological roles.
Two calcium-dependent phospholipid- and membrane-binding proteins have been purified from bovine brain. These are termed CaBP33 and CaBP37. Complete sequence analysis has revealed that these two proteins are isoforms of annexin V. Despite an apparent difference of 4 kDa between the two proteins on SDS-PAGE, only two amino-acid substitutions were found. These are, in CaBP33, Ser-36 and Lys-125 and in CaBP37, Thr-36 and Glu-125. This corresponds to a mass difference of 15 Da. This was confirmed by electrospray mass spectrometric analysis. Both isoforms can be phosphorylated substoichiometrically in vitro by protein kinase C at residue Thr-22.
Learmonth
M P
MP
Laboratory of Protein Structure, National Institute for Medical Research, Mill Hill, London, UK.
Howell
S A
SA
Harris
A C
AC
Amess
B
B
Patel
Y
Y
Giambanco
I
I
Bianchi
R
R
Pula
G
G
Ceccarelli
P
P
Donato
R
R
D000595:Amino Acid Sequence; D000818:Animals; D017304:Annexin A5 / Q000737:chemistry* / Q000302:isolation & purification; D001923:Brain Chemistry; D002417:Cattle; D005973:Glutamine; D008239:Lysine; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D016415:Sequence Alignment; D012694:Serine; D013912:Threonine / Q000378:metabolism
D017304:Annexin A5; D008565:Membrane Proteins; D005973:Glutamine; D013912:Threonine; D012694:Serine; D011493:Protein Kinase C; D008239:Lysine