Organization of the functional domains in membrane cytoskeletal protein talin.
Talin, a putative homodimer of 230-kDa polypeptides, was cleaved into the N-terminal 47-kDa and C-terminal 190-kDa fragments with calpain II. The 190-kDa fragment, but not the 47-kDa fragment, was found to bind to actin. The 190-kDa fragment possessed similar levels of activities to stimulate both polymerization of G-actin and alpha-actinin-dependent gelation of F-actin as did intact talin. Limited digestions of the 190-kDa fragment with chymotrypsin and papain resulted in partial and complete reductions, respectively, of both activities, although these digests contained 95- and 46-kDa major polypeptides, respectively, which were able to bind to actin. Whereas the 190-kDa fragment generated fully cross-linked oligomeric polypeptides on treatment with 1-ethyl-3[3-(dimethylamino)-propyl]carbodiimide, the 95-kDa chymotryptic polypeptide generated heterologous polypeptides cross-linked partially with smaller polypeptides. The papain digest did not contain any cross-linkable polypeptide. Intact talin and the 47-kDa calpain fragment, but not the 190-kDa calpain fragment, were found to bind to phospholipid vesicles containing phosphatidylserine. These results indicate that the N-terminal and C-terminal domains play distinct roles in interacting with the membrane and cytoskeletal elements, respectively, and that the dimeric structure is also required for the latter interactions.
Muguruma
M
M
Department of Animal Science, Faculty of Agriculture, Kyushu University, Fukuoka.
Nishimuta
S
S
Tomisaka
Y
Y
Ito
T
T
Matsumura
S
S
D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002154:Calpain / Q000737:chemistry / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002645:Chickens; D002918:Chymotrypsin / Q000737:chemistry / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000502:physiology; D003599:Cytoskeleton / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000502:physiology; D015394:Molecular Structure; D010206:Papain / Q000737:chemistry / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D010743:Phospholipids / Q000378:metabolism; D011108:Polymers; D011817:Rabbits; D016608:Talin / Q000737:chemistry* / Q000494:pharmacology / Q000502:physiology
D000199:Actins; D003598:Cytoskeletal Proteins; D008081:Liposomes; D008565:Membrane Proteins; D010446:Peptide Fragments; D010743:Phospholipids; D011108:Polymers; D016608:Talin; D002918:Chymotrypsin; D002154:Calpain; D010206:Papain