title: Human plasma lipocalins and serum albumin: Plasma alternative carriers?
abstract: Lipocalins are an evolutionarily conserved family of proteins that bind and transport a variety of exogenous and endogenous ligands. Lipocalins share a conserved eight anti-parallel β-sheet structure. Among the different lipocalins identified in humans, α-1-acid glycoprotein (AGP), apolipoprotein D (apoD), apolipoprotein M (apoM), α1-microglobulin (α1-m) and retinol-binding protein (RBP) are plasma proteins. In particular, AGP is the most important transporter for basic and neutral drugs, apoD, apoM, and RBP mainly bind endogenous molecules such as progesterone, pregnenolone, bilirubin, sphingosine-1-phosphate, and retinol, while α1-m binds the heme. Human serum albumin (HSA) is a monomeric all-α protein that binds endogenous and exogenous molecules like fatty acids, heme, and acidic drugs. Changes in the plasmatic levels of lipocalins and HSA are responsible for the onset of pathological conditions associated with an altered drug transport and delivery. This, however, does not necessary result in potential adverse effects in patients because many drugs can bind both HSA and lipocalins, and therefore mutual compensatory binding mechanisms can be hypothesized. Here, molecular and clinical aspects of ligand transport by plasma lipocalins and HSA are reviewed, with special attention to their role as alterative carriers in health and disease.
authors.affiliation: Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, I-00146 Roma, Italy; Istituto Nazionale di Biostrutture e Biosistemi, Via delle Medaglie d'Oro 305, I-00136 Roma, Italy. Electronic address: alessandra.dimasi@uniroma3.it.
authors.forename: Alessandra
authors.initials: A
authors.lastname: di Masi
authors.affiliation: Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, I-00146 Roma, Italy.
authors.forename: Viviana
authors.initials: V
authors.lastname: Trezza
authors.affiliation: Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, I-00146 Roma, Italy; Istituto Nazionale di Biostrutture e Biosistemi, Via delle Medaglie d'Oro 305, I-00136 Roma, Italy.
authors.forename: Loris
authors.initials: L
authors.lastname: Leboffe
authors.affiliation: Istituto Nazionale di Biostrutture e Biosistemi, Via delle Medaglie d'Oro 305, I-00136 Roma, Italy; Laboratorio Interdipartimentale di Microscopia Elettronica, Università Roma Tre, Via della Vasca Navale 79, I-00146 Roma, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Ascenzi
mesh_terms: D001692:Biological Transport; D004337:Drug Carriers / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D054834:Lipocalins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D004364:Pharmaceutical Preparations / Q000008:administration & dosage / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004337:Drug Carriers; D008024:Ligands; D054834:Lipocalins; D004364:Pharmaceutical Preparations; D012709:Serum Albumin
keywords: Drug carrier; Drug delivery; Human serum albumin; Ligand binding properties; Plasma lipocalins