M. Muguruma et al., ORGANIZATION OF THE FUNCTIONAL DOMAINS IN MEMBRANE CYTOSKELETAL PROTEIN TALIN, Journal of Biochemistry, 117(5), 1995, pp. 1036-1042
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-depende
nt 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, whi
ch 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 polyp
eptide generated heterologous polypeptides cross-linked partially with
smaller polypeptides, The papain digest did not contain any cross-lin
kable polypeptide. Intact talin and the 47-kDa calpain fragment, but n
ot the 190-kDa calpain fragment, were found to bind to phospholipid ve
sicles containing phosphatidylserine, These results indicate that the
N-terminal and C-terminal domains play distinct roles in interacting w
ith the membrane and cytoskeletal elements, respectively, and that the
dimeric structure is also required for the latter interactions.