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Real human tissue factor
Author(s) -
Butenas Saulius,
BrummelZiedins Kathleen,
Mann Kenneth
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a47-a
Subject(s) - recombinant dna , chemistry , tissue factor , monocyte , human blood , bioassay , biological activity , microbiology and biotechnology , biochemistry , in vitro , biology , immunology , medicine , coagulation , physiology , genetics , gene
The presence, concentration and activity of tissue factor (TF) circulating in blood are controversial. Data fueling these controversies are largely related to the use of bioassays with recombinant TF proteins (rTF) as standards. We compared full‐length rTF 1‐263 with the isolated natural placental (pTF) and monocyte (mTF) proteins. The latter two are equivalent by SDS‐PAGE (Mw app =45,000). By mass‐spectroscopy, pTF protein has a higher molecular weight (36,179) than rTF 1‐263 (32,705) indicating different post‐translational modifications. In complex with factor VIIa, pTF is more active than rTF 1‐263 in assays using a fluorogenic peptide substrate (~3‐fold; with and without phospholipids), in factor X activation (~3‐fold), in synthetic (~2‐fold) and natural (~3‐fold) plasma and in contact pathway‐inhibited whole blood (~2‐fold). Comparisons of purified and relipidated TF with mTF presented on LPS‐stimulated monocytes in situ showed that the latter is more active by up to 400‐fold over isolated and relipidated mTF. Overall, our data show: 1) The mass and functional activities of rTF are less than those of natural TF; 2) TF properties are dramatically influenced by post‐translational modification and the cellular TF environment. Thus the quantitation of TF based on functional assays must be treated with extreme caution. Supported by P01 46703 grant from the NIH.