PDBsum entry 1cdh

T-cell surface glycoprotein

PDB id: 1cdh

Contents

Protein chain

178 a.a. *

Waters ×86

* Residue conservation analysis

PDB id:

1cdh

Name:

T-cell surface glycoprotein

Title:

Structures of an HIV and mhc binding fragment from human cd4 as refined in two crystal lattices

Structure:

T cell surface glycoprotein cd4. Chain: a. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Organ: ovary

Resolution:

2.30Å R-factor: 0.193

Authors:

S.E.Ryu,A.Truneh,R.W.Sweet,W.A.Hendrickson

Key ref:

S.E.Ryu et al. (1994). Structures of an HIV and MHC binding fragment from human CD4 as refined in two crystal lattices. Structure, 2, 59-74. PubMed id: 8075984 DOI: 10.1016/S0969-2126(00)00008-3

Date:

26-Jan-94 Release date: 30-Apr-94

Supersedes:

1cd4

Protein chain

P01730  (CD4_HUMAN) -  T-cell surface glycoprotein CD4 from Homo sapiens

Seq: 458 a.a.

Struc: 178 a.a.

DOI no: 10.1016/S0969-2126(00)00008-3

Structure 2:59-74 (1994)

PubMed id: 8075984

Structures of an HIV and MHC binding fragment from human CD4 as refined in two crystal lattices.

S.E.Ryu, A.Truneh, R.W.Sweet, W.A.Hendrickson.

ABSTRACT

BACKGROUND: The T-cell surface glycoprotein CD4 interacts with class II molecules of the major histocompatibility complex (MHC) enhancing the signal for T-cell activation. Human CD4 also interacts, at high affinity, with the HIV envelope glycoprotein, gp120, to mediate T-cell infection by HIV. Crystal structures of amino-terminal two-domain (D1D2) fragments of human CD4, which contain the residues implicated in HIV and MHC interactions, have been reported earlier. RESULTS: We have determined the crystal structure of a new D1D2 construct by molecular replacement from a previously described crystal structure of D1D2. This structure has more uniform lattice contacts than are in the first. This gives an improved image of domain D2, which in turn has permitted further refinement of the initial structure at 2.3 A resolution against a more complete data set. The structure of the second crystal form was also refined at 2.9 A resolution. In both models, all residues from 1 to 178 are now well defined, including the loop regions in D2. CONCLUSIONS: Similarities of the molecular structure in the two lattices suggest that the D1D2 fragment works as a unit, with segmental flexibility largely restricted to the junction between domains D2 and D3. Variability of conformation in loops, including those implicated in MHC and HIV binding, requires an 'induced fit' in these interactions. Well defined density for the exposed side chain of Phe43 in both crystals confirms a prominent role for this residue in gp120 binding.

Selected figure(s)

Figure 4.
Figure 4. B-factor distribution of the refined two crystal structures, showing B-factors of C[α]atoms. The average B-factor for all the residues, D1 residues and D2 residues are 29.8 å^2, 23.0 å^2and 38.3 å^2in the type I crystal form, and 13.7 å^2, 14.7 å^2and 12.5 å^2in the type II crystal form. Figure 4. B-factor distribution of the refined two crystal structures, showing B-factors of C[α]atoms. The average B-factor for all the residues, D1 residues and D2 residues are 29.8 å^2, 23.0 å^2and 38.3 å^2in the type I crystal form, and 13.7 å^2, 14.7 å^2and 12.5 å^2in the type II crystal form.

Figure 11.
Figure 11. CDR2-like region implicated in binding interactions. The region from the C′ C″ β-turn through strand C″ and into loop C″ D (residues 40–52) is shown from the superposition of the two structures based on all C[α]positions. Type I and II structures are shown in red and blue, respectively. Figure 11. CDR2-like region implicated in binding interactions. The region from the C′ C″ β-turn through strand C″ and into loop C″ D (residues 40–52) is shown from the superposition of the two structures based on all C[α]positions. Type I and II structures are shown in red and blue, respectively.

The above figures are reprinted by permission from Cell Press: Structure (1994, 2, 59-74) copyright 1994.

Figures were selected by an automated process.