Title : The alpha and beta chains of human platelet
glycoprotein Ib are both transmembrane
proteins containing a
leucine-rich amino acid
sequence
Abstract :
- The primary structure of the beta chain of human glycoprotein Ib (GPIb), the platelet receptor for von Willebrand factor , has been established by a combination of cDNA cloning and amino acid sequence analysis
- A lambda phage cDNA expression library prepared from human erythroleukemia cells (HEL cells) was screened with a radiolabeled affinity-purified rabbit polyclonal antibody to the beta chain of GPIb
- Eighteen positive clones were isolated and plaque-purified and the nucleotide sequences of three were determined
- The composite sequence spanned 968 nucleotides and included a 5' untranslated region of 22 nucleotides, an open reading frame of 618 nucleotides encoding a signal peptide of 28 amino acids and a mature protein of 181 amino acids, a stop codon, and a 3' noncoding region of 307 nucleotides
- The 3' noncoding sequence also contained a polyadenylylation signal (AATAAA) 14 nucleotides upstream from the poly(A) tail of 18 nucleotides
- Edman degradation of the intact beta chain and of peptides produced by chemical cleavage yielded amino acid sequences spanning 76 residues that were identical to those predicted from the cDNA
- The amino-terminal region of the beta chain contains a leucine-rich sequence of 24 amino acids that is similar to a sequence that occurs as seven tandem repeats in the alpha chain of GPIb and nine tandem repeats in leucine-rich alpha 2-glycoprotein
- The leucine-rich sequence in the beta chain of GPIb is flanked on both sides by amino acid sequences that are similar to those flanking the leucine-rich tandem repeats of the alpha chain of GPIb and leucine-rich alpha 2-glycoprotein
- The amino-terminal region of the beta chain of GPIb is followed by a transmembrane segment of 25 amino acids and an intracellular segment of 34 amino acids at the carboxyl terminus of the protein
- The intracellular segment contains an unpaired cysteine and two potential sites for phosphorylation by cAMP-dependent protein kinase
Output (sent_index, trigger,
protein,
sugar,
site):
- 0. glycoprotein, , glycoprotein, -, -
- 1. glycoprotein, , glycoprotein, -, -
- 8. leucine-rich, , -, the leucine-rich tandem repeats, leucine
Output(Part-Of) (sent_index,
protein,
site):
- 0. proteins, sequence
- 7. -, sequence
- 9. protein, terminus
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):