| Literature References | 1. LAWLER, J. AND HYNES, R.O.
The structure of human thrombospondin, an adhesive glycoprotein with
multiple calcium-binding sites and homologies with several different
proteins.
J.CELL BIOL. 103(5) 1635-1648 (1986).
2. ADAMS, J.C. AND TUCKER, R.P.
The thrombospondin type 1 repeat (TSR) superfamily: diverse proteins with
related roles in neuronal development.
DEV.DYN. 218(2) 280-299 (2000).
3. SMITH, K.F., NOLAN, K.F., REID, K.B. AND PERKINS, S.J.
Neutron and X-ray scattering studies on the human complement protein
properdin provide an analysis of the thrombospondin repeat.
BIOCHEMISTRY 30(32) 8000-8008 (1991).
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| Documentation | The TSP1 (thrombospondin 1) repeat was first identified in the
thrombospondin protein, where it is repeated 3 times [1]. The domain is
~60 amino acid residues in length and is characterised by a highly
conserved W-S-X-W motif and six cysteine residues [2]. TSP1 repeats have
been identified in a number of proteins including: the complement pathway
proteins properdin, C6, C7, C8A, C8B and C9; extracellular matrix proteins,
including mindin, ADAMTS and F-spondin; Plasmodium TRAP proteins; and G
protein-coupled receptors, such as the brain-specific angiogenesis
inhibitors [2]. The domains have a number of functions, including effects
on cell attachment, motility, proliferation, the activities of extracellular
proteases, and inhibition of angiogenesis, contributing to vascular
homeostasis [2]. A study of the structure of properdin indicates that the
TSP1 repeat contains two amphipathic turn regions and a hydrophilic
beta-strand [3].
TSP1REPEAT is a 3-element fingerprint that provides a signature for the
thrombospondin type 1 repeat. The fingerprint was derived from an initial
alignment of 5 sequences: the motifs were drawn from conserved regions
spanning the full length of the domain - motif 1 encodes the well-conserved
N-terminal portion, including the W-S-X-W motif; and motifs 2 and 3 span the
less conserved central and C-terminal portions of the repeat, respectively.
Four iterations on SPTR40_18f were required to reach convergence, at which
point a true set comprising 87 sequences was identified. Numerous partial
matches were also found: all are thrombospondin repeat-containing proteins
that fail to match one of the motifs.
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