Comparative modeling of the N-terminal domain of the 67kDa laminin-binding protein: implications for putative ribosomal function.
Laminin-binding protein/p40 (LBP/p40) precursor appears to be involved in two seemingly unrelated activities-cell adhesion and ribosomal biogenesis. Analysis of primary structure revealed a two-domain organization of the LBP/p40. The N-terminal portion of LBP is similar to the S2 family of prokaryotic ribosomal proteins, while the C-terminus is unique for Metazoa and is involved in extraribosomal functions. To gain insight into putative ribosomal functions of LBP we performed comparative modeling of the N-terminal domain using crystal structures of S2p from Thermus thermophilus. The LBP model assumes an alpha-beta sandwich fold similar to that of S2. Modeling revealed the loss of a significant portion of ribosomal RNA (rRNA) interaction domain, lack of conservation of many residues involved in interactions with rRNA, and a major shift in surface charge distribution (compared to the S2 protein). The overall stability of the fold argues against a proposed transmembrane domain in the central part of the protein. Partial overlap in S2 and laminin-binding domains suggests that ribosomal and surface receptor functions would be mutually exclusive. The possible biological role of LBP/p40 bifunctionality is discussed.
Kazmin
Dmitri A
DA
Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA.
Chinenov
Yurii
Y
Larson
Eric
E
Starkey
Jean R
JR
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D006801:Humans; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011485:Protein Binding; D011498:Protein Precursors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012335:RNA, Ribosomal / Q000737:chemistry / Q000378:metabolism; D017474:Receptors, Laminin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D016963:Thermus thermophilus / Q000737:chemistry / Q000235:genetics
D001426:Bacterial Proteins; D046911:Macromolecular Substances; D011498:Protein Precursors; D012335:RNA, Ribosomal; D017474:Receptors, Laminin; D012269:Ribosomal Proteins; C030004:ribosomal protein S2