PDBsum entry 4l41

Calcium binding protein/transferase

PDB id: 4l41

Contents

Protein chains

123 a.a.

273 a.a.

Ligands

SO4

Metals

_CA ×2

Waters ×31

PDB id:

4l41

Name:

Calcium binding protein/transferase

Title:

Human lactose synthase: a 2:1 complex between human alpha-lactalbumin and human beta1,4-galactosyltransferase

Structure:

Alpha-lactalbumin. Chain: a, b. Fragment: unp residues 19-142. Synonym: lactose synthase b protein, lysozyme-like protein 7. Engineered: yes. Beta-1,4-galactosyltransferase 1. Chain: c. Fragment: unp residues 126-398. Synonym: beta-1,4-galtase 1, beta4gal-t1, b4gal-t1.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: 4-galactosyltransferase, beta1, lalba, lyzl7. Expressed in: escherichia coli. Expression_system_taxid: 511693. Gene: alpha-lactalbumin, b4galt1, ggtb2.

Resolution:

2.70Å R-factor: 0.190 R-free: 0.237

Authors:

B.Ramakrishnan,P.K.Qasba

Key ref:

B.Ramakrishnan and p.k.qasba Crystal structure of human lactose synthase forms a n 1:2 complex between beta1,4galactosyltransferase 1 an alpha-Lactalbumin proteins. To be published, .

Date:

07-Jun-13 Release date: 02-Oct-13

Protein chains

P00709  (LALBA_HUMAN) -  Alpha-lactalbumin from Homo sapiens

Seq: 142 a.a.

Struc: 123 a.a.

Protein chain

P15291  (B4GT1_HUMAN) -  Beta-1,4-galactosyltransferase 1 from Homo sapiens

Seq: 398 a.a.

Struc: 273 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class 1: Chain C: E.C.2.4.1.- - ?????
• Enzyme class 2: Chain C: E.C.2.4.1.22 - lactose synthase.
• Reaction: D-glucose + UDP-alpha-D-galactose = lactose + UDP + H⁺
• Enzyme class 3: Chain C: E.C.2.4.1.275 - neolactotriaosylceramide beta-1,4-galactosyltransferase.
• Reaction: a beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-beta-D-Glc-(1<->1)- Cer(d18:1(4E)) + UDP-alpha-D-galactose = a neolactoside nLc4Cer(d18:1(4E)) + UDP + H⁺
• Enzyme class 4: Chain C: E.C.2.4.1.38 - beta-N-acetylglucosaminylglycopeptide beta-1,4-galactosyltransferase.
• Reaction: an N-acetyl-beta-D-glucosaminyl derivative + UDP-alpha-D-galactose = a beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl derivative + UDP + H⁺
• Enzyme class 5: Chain C: E.C.2.4.1.90 - N-acetyllactosamine synthase.
• Reaction: N-acetyl-D-glucosamine + UDP-alpha-D-galactose = beta-D-galactosyl- (1->4)-N-acetyl-D-glucosamine + UDP + H⁺

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site