The disulfide bond pattern of catrocollastatin C, a disintegrin-like/cysteine-rich protein isolated from Crotalus atrox venom

The disulfide bond pattern of catrocollastatin-C was determined by N-terminal sequencing and mass spectrometry. The N-terminal disintegrin-like domain is a compact structure including eight disulfide bonds, seven of them in the same pattern as the disintegrin bitistatin. The protein has two extra cysteine residues (XIII and XVI) that form an additional disulfide bond that is characteristically found in the disintegrin-like domains of cellular metalloproteinases (ADAMs) and PIII snake venom Zn-metalloproteinases (SVMPs). The C-terminal cysteine-rich domain of catrocollastatin-C contains five disulfide bonds between nearest-neighbor cysteines and a long range disulfide bridge between CysV and CysX. These results provide structural evidence for a redefinition of the disintegrin-like and cysteine-rich domain boundaries. An evolutionary pathway for ADAMs, PIII, and PII SVMPs based on disulfide bond engineering is also proposed.

Relationship of tumoral hyaluronic acid and cathepsin D contents with histological type of gastric carcinoma

The aim of this work was to evaluate the cytosolic contents of hyaluronic acid (HA) and cathepsin D (CatD) in gastric carcinomas and their possible relationships with the clinicopathological parameters of the tumors. Our study demonstrated a wide variability in the cytosolic levels of HA (mean +/- SEM: 3748 +/- 411 ng/mg protein) and cathepsin D (52 +/- 4 pmol/mg protein) in the tumors of 78 gastric cancer patients. In addition, the tumoral contents of HA and CatD were significantly higher (p<0.005) in diffuse type (HA: 6027 +/- 1099 ng/mg protein; CatD: 75 +/- 13 pmol/mg protein) than in intestinal type (HA: 2735 +/- 242 ng/mg protein; CatD: 42 +/- 3 pmol/mg protein) carcinomas. These data suggest that both markers may contribute to the biological characterization of gastric carcinomas.

The atypical PKC-interacting protein p62 channels NF-kappaB activation by the IL-1-TRAF6 pathway

The atypical protein kinase C (aPKC)-interacting protein, p62, has previously been shown to interact with RIP, linking these kinases to NF-kappaB activation by tumor necrosis factor alpha (TNFalpha). The aPKCs have been implicated in the activation of IKKbeta in TNFalpha-stimulated cells and have been shown to be activated in response to interleukin-1 (IL-1). Here we demonstrate that the inhibition of the aPKCs or the down-regulation of p62 severely abrogates NF-kappaB activation by IL-1 and TRAF6, suggesting that both proteins are critical intermediaries in this pathway. Consistent with this we show that p62 selectively interacts with the TRAF domain of TRAF6 but not that of TRAF5 or TRAF2 in co-transfection experiments. The binding of endogenous p62 to TRAF6 is stimulus dependent, reinforcing the notion that this is a physiologically relevant interaction. Furthermore, we demonstrate that the N-terminal domain of TRAF6, which is required for signaling, interacts with zetaPKC in a dimerization-dependent manner. Together, these results indicate that p62 is an important intermediary not only in TNFalpha but also in IL-1 signaling to NF-kappaB through the specific adapters RIP and TRAF6.

[Pulse rate of the venous wave in the eco-Doppler study of the lower extremities as a sign of elevated pressure in the right atrium]

AIM

The aim of this study is to determine the nature of venous flow in the lower extremities, as well as to correlate the velocity of the flow with average vein pressure in the right atrium.

MATERIAL AND METHODS

Over a period of one year 236 pulsated Doppler echographs were made of patients, bearers of a venous catheter located in the right atrium. The patients were in a supine lying position and breathing gently. The lines of the Doppler wave were used to analyse the frequency of the wave, the components of its velocity, the relationships of velocity and the existence of pulsatile flow. These parameters were compared with the pressure in the right atrium.

RESULTS

The study showed a cardiac and respiratory periodicity of the venous wave. A statistically significant correlation (p<0.0001) was found between average venous pressure in the right atrium and the following variables: the systolic atrium wave (a), the diastolic atrium wave (d), the relation of pulsatility (RP=Velocity min/Velocity max) and the index of pulsatility (IP=[Velocity max-Velocity min]/Velocity average).

CONCLUSION

There is an inverse and significant relationship between pulsatile flow and atrium pressure. Nonetheless, although a relation exists between the different components of the venous wave, an elevation in central vein pressure cannot be predicted.

Structural characterization of the oligosaccharide chains of native and crystallized boar seminal plasma spermadhesin PSP-I and PSP-II glycoforms

The PSP-I/PSP-II heterodimer is the major protein of boar seminal plasma. Both subunits are glycoproteins of the spermadhesin family and each contains a single N-glycosylation site. After enzymatic release of the oligosaccharides from isolated PSP-I and PSP-II, mainly neutral and monosialylated oligosaccharides, and small amounts of disialylated oligosaccharides, were recovered from both proteins. Twenty-two neutral oligosaccharides, 11 monosialylated glycans and three disialylated carbohydrate chains were characterized using mass spectrometric and NMR techniques. PSP-I and PSP-II share the same glycans but differ in their relative molar ratios. Most glycan structures are proximally alpha1-6-fucosylated, diantennary complex-type bearing nonsialylated or alpha2-6-sialylated N-acetyllactosamine or di-N-acetyllactosamine antennae. The majority of nonsialylated N-acetyllactosamine antennae bear terminal alpha1-3-linked Gal residues. In addition, the N-acetylglucosamine residue of nonsialylated N-acetyl and di-N-acetyllactosamine antennae can be modified by an alpha1-3-linked fucose residue. Structures of higher antennarity, as well as structures 3,6-branched at galactose residues, were found in smaller amounts. In one oligosaccharide, N-acetylneuraminic acid is substituted by N-glycolylneuraminic acid. Mass spectrometric analysis of PSP-I and PSP-II glycoforms isolated from crystallized PSP-I/PSP-II heterodimer showed the coexistence of major PSP-I and PSP-II glycoforms in the hexagonal crystals. Oligosaccharides with the NeuNAcalpha2-6GalNAcbeta1-4GlcNAc-R motif block adhesive and activation-related events mediated by CD22, suggesting a possible immunoregulatory activity for PSP-I/PSP-II.

Pattern of recurrence after esophageal resection for cancer

BACKGROUND/AIMS

Surgery is still the main treatment option for esophageal cancer; however, long-term survival has remained poor, even when a curative operation is performed. The present study was undertaken to analyze the pattern and time of recurrence after a curative esophagectomy.

METHODOLOGY

We studied 53 patients who underwent curative esophageal resection for cancer between 1985 and 1994. We examined number and pattern of recurrences, time after surgery, and any factor with contribution to carcinoma recurrence.

RESULTS

During the follow-up period, 34 patients had tumor recurrence. The disease-free interval was 12.7 months (SD = 9.8). Twenty patients (58.9%) developed extrathoracic tumor recurrence and 23 patients (67.6%) intrathoracic. In 3 cases an esophageal stump recurrence was presented. Thirteen patients were considered for palliative treatment after recurrence. The 5-year survival rate was 13%, with median survival time between recurrence and death, 4.1 months. The recurrence of disease was always before 40 months after surgery. Any significant difference related with recurrence was observed between the analyzed factors.

CONCLUSIONS

The majority of recurrences are developed before 2 years. Neoplastic recurrence is most common at the mediastinum. Palliative treatments after recurrence do not modify the progression of tumor.

The interaction of p62 with RIP links the atypical PKCs to NF-kappaB activation

The two members of the atypical protein kinase C (aPKC) subfamily of isozymes (zetaPKC and lambda/iotaPKC) are involved in the control of nuclear factor kappaB (NF-kappaB) through IKKbeta activation. Here we show that the previously described aPKC-binding protein, p62, selectively interacts with RIP but not with TRAF2 in vitro and in vivo. p62 bridges the aPKCs to RIP, whereas the aPKCs link IKKbeta to p62. In this way, a signaling cascade of interactions is established from the TNF-R1 involving TRADD/RIP/p62/aPKCs/IKKbeta. These observations define a novel pathway for the activation of NF-kappaB involving the aPKCs and p62. Consistent with this model, the expression of a dominant-negative mutant lambda/iotaPKC impairs RIP-stimulated NF-kappaB activation. In addition, the expression of either an N-terminal aPKC-binding domain of p62, or its C-terminal RIP-binding region are sufficient to block NF-kappaB activation. Furthermore, transfection of an antisense construct of p62 severely abrogates NF-kappaB activation. Together, these results demonstrate that the interaction of p62 with RIP serves to link the atypical PKCs to the activation of NF-kappaB by the TNFalpha signaling pathway.

A new HLA-Cw*15 allele, Cw*1508, identified in the Peruvian population

A novel HLA-Cw*15 allele , Cw*1508, has been found in the Peruvian population. This new allele, initially detected as a polymerase chain reaction with sequence-specific primers (PCR-SSP) variant, shows greatest similarity to Cw*1502. The nucleotide sequence of Cw*1508 only differs from that of Cw*1502 at position 539; this change determines the replacement of Leu by Arg 156 in Cw*1508.

Variables aggregation in a time discrete linear model

In this work we extend approximate aggregation methods to deal with a very general linear time discrete model. Approximate aggregation consists in describing some features of the dynamics of a general system in terms of the dynamics of a reduced system governed by a few global variables. We present a time discrete model for a structured population (i.e., the population is subdivided in subpopulations) in which we can distinguish two processes of a general nature and whose corresponding time scales are very different from each other. We transform the general system to make the global variables appear and obtain the reduced system. These global variables are, for each subpopulation, a certain linear combination of the corresponding state variables. We show that, under quite general conditions, the asymptotic behavior of the reduced system can be known in terms of the corresponding behavior for the reduced system. The general method is applied to aggregate a multiregional Leslie model in which the demographic process is supposed to be fast with respect to migration.

Characterisation of the conformational and quaternary structure-dependent heparin-binding region of bovine seminal plasma protein PDC-109

PDC-109, the major heparin-binding protein of bull seminal plasma, binds to sperm choline lipids at ejaculation and modulates capacitation mediated by heparin. Affinity chromatography on heparin-Sepharose showed that polydisperse, but not monomeric, PDC-109 displayed heparin-binding capability. We sought to characterise the surface topology of the quaternary structure-dependent heparin-binding region of PDC-109 by comparing the arginine- and lysine-selective chemical modification patterns of the free and the heparin-bound protein. A combination of reversed-phase peptide mapping of endoproteinase Lys-C-digested PDC-109 derivatives and mass spectrometry was employed to identify modified and heparin-protected residues. PDC-109 contains two tandemly arranged fibronectin type II domains (a, Cys24-Cys61; b, Cys69-Cys109). The results show that six basic residues (Lys34, Arg57, Lys59, Arg64, Lys68, and Arg104) were shielded from reaction with acetic anhydride and 1,2-cyclohexanedione in heparin-bound PDC-109 oligomers. In the 1H-NMR solution structures of single fibronectin type II domains, residues topologically equivalent to PDC-109 Arg57 (Arg104) and Lys59 lay around beta-strand D on the same face of the domain. In full-length PDC-109, Arg64 and Lys68 are both located in the intervening polypeptide between domains a and b. Our data suggest possible quaternary structure arrangements of PDC-109 molecules to form a heparin-binding oligomer.

Spermadhesins: a new protein family. Facts, hypotheses and perspectives

Spermadhesins are a novel family of secretory proteins expressed in the male genital tract of pig, horse and bull. They are major products of the seminal plasma and have been found to be peripherally associated to the sperm surface. The structure and function of spermadhesins have been thoroughly investigated in the pig, which exhibits the greatest diversity of members: AWN, AQN-1, AQN-2, PSP-I and PSP-II and its glycosylated isoforms. They are multifunctional proteins showing a range of ligand-binding abilities, e.g. carbohydrates, sulfated glycosaminoglycans, phospholipids and protease inhibitors, suggesting that they may be involved in different steps of fertilization. Isolated porcine spermadhesins bind the zona pellucida glycoproteins in a cation-dependent manner with a Kd in a low micromolar range, and AWN, AQN-1 and AQN-3 display similar binding affinity for glycoproteins containing Gal beta(1-3)-GalNAc and Gal beta(1-4)-GlcNAc sequences in O-linked and N-linked oligosaccharides, respectively. During sperm passage through the epididymis AQN-3 and AWN have been shown to bind tightly to the sperm surface by interaction with the phospholipids of the membrane bilayer. At ejaculation the spermadhesins form a protective coat around the sensitive acrosomal region of the sperm head, thus possibly preventing premature acrosome reaction. During in vitro capacitation most of these aggregated sperm adhesins are lost, with the exception of phospholipid-bound spermadhesins. AWN and AQN-3 may now serve as a primary receptor for the oocyte zona pellucida, thus contributing to initial binding and recognition between sperm and egg. The amino acid sequence of spermadhesins does not show any discernible similarity with known carbohydrate recognition domains (CRD). However, they belong to the superfamily of proteins with a CUB domain with a predicted all-beta structure. The crystal structure of the heterodimeric complex of the spermadhesins PSP-I/PSP-II has been solved, showing that the overall structure of both spermadhesins consists of a beta-sandwich with five (parallel and antiparallel) beta-strands. It is the first three-dimensional structure of a zona pellucida-binding protein and reveals the architecture of the CUB domain. The spermadhesins represent a novel class of lectins that may be involved in sequential steps of fertilization, at least in the pig.

Risk of relapse and clinico-pathological features in 103 patients with diffuse large-cell lymphoma in complete response after first-line treatment

Patients with diffuse large-cell lymphoma (DLCL) achieve a complete response (CR) in most cases, but at least one-third of them eventually relapse. Such an event occurs most frequently within 2 yr from CR achievement. The aim of the present study was to analyse the risk and pattern of relapse of patients with DLCL in CR. One hundred and three patients with DLCL (53 male/50 female; median age: 55 yr) in CR after doxorubicin-containing first-line treatments were included in the study. Main clinicobiological characteristics at diagnosis and at relapse were analysed. Uni- and multivariate studies were performed. Forty-one patients (40%) eventually relapsed, in 27 cases within 2 yr from CR and 14 thereafter. Histological subtype was the same at diagnosis and at relapse in all the early relapsing patients and in 8 of 10 late relapsing patients with available biopsy. The most important variables at diagnosis for predicting relapse were advanced stage (p<0.01) and bone marrow infiltration (p=0.05), with stage (I-II vs. III-IV) (p=0.009; relative risk=2.28) being the only predictive variable in the multivariate analysis. No differences were found according to the treatment given. The second CR rate obtained in the late relapsing patients after salvage therapies was higher that in early relapsing (50% vs. 37%). Median survival from relapse was 1.4 yr for patients early relapsing and it was not achieved for those with late relapses (p=0.09). Late relapse is a quite common event in DLCL lymphomas, with those patients achieving more frequently a second CR and having better survival than early relapsed patients.

[Contribution of magnetic resonance to the differential diagnosis of a collapsed vertebra in a patient with multiple myeloma]

The only safe method to determine whether or not patients diagnosed of smoldering myeloma will progress to symptomatic multiple myeloma (MM) is periodic follow-up. In the last years, several studies have emphasized the efficacy of magnetic resonance imaging (MRI) to detect bone marrow involvement in these patients. However, the detection of a focal spinal lesion in elderly patients raises a diagnostic problem, sometimes difficult to solve, between a benign or malignant origin. We present the case of an elderly women with marked osteoporosis and smoldering myeloma who suddenly complained of pain in dorsal spine. MRI showed focal lesions in two dorsal vertebra consistent with myeloma involvement. However, there were no other signs of progression, the lesions were considered secondary to osteoporosis and calcitonin was administered. This resulted in the disappearance of the pain and the MRI abnormalities, which confirmed its benign etiology. The role and limitations of MRI to detect bone marrow involvement by MM in the evaluation of these patients is reviewed.

HLA-Cw*1602: a new susceptibility marker of Behçet's disease in southern Spain

Genotyping of the HLA-C locus by PCR-SSP in Behçet's disease patients from southern Spain reveals a statistically significant association with Cw*1602 (OR 20.15, corrected p < 0.05). This is an uncommon allele absent from the healthy control group, which seems to confer higher relative risk than B51 in this study (OR 1.85). Stratified frequencies do not show statistically significant differences but suggest that the Cw*1602-B51 haplotype could be the main HLA marker of Behçet's disease in the analyzed population.

Conformational features and thermal stability of bovine seminal plasma protein PDC-109 oligomers and phosphorylcholine-bound complexes

At ejaculation, PDC-109, the major heparin-binding protein of bull seminal plasma, binds to the phosphorylcholine group of sperm lipids and modulates capacitation promoted by glycosaminoglycans during sperm residence in the female genital tract. Combination of size-exclusion chromatography, analytical ultracentrifugation, circular dichroism, Fourier-transform infrared spectroscopy, and differential scanning calorimetry has allowed us to biophysically characterize PDC-109 and its interaction with phosphorylcholine. PDC-109 can be regarded as a polydisperse molecule whose aggregation state can be modulated by the solute composition of its solution environment. Dissociation of PDC-109 oligomers occurs upon increasing the concentration of either NaCl, EDTA, CaCl2, or phosphorylcholine, suggesting that both ionic and hydrophobic interactions are responsible for the aggregation tendency of PDC-109 monomers. Dissociation processes are accompanied by exposure of peptide bonds to the solvent, changes in the environment of tyrosine and tryptophan residues, and a slight increase in the turn content at the expense of non-regular structure. Analysis of the heat-induced denaturation of PDC-109 oligomers revealed two melting transitions at about 36 degrees C (irreversible) and 55 degrees C (partially reversible) characterized by calorimetric enthalpy changes of 42 kJ/mol and 217 kJ/mol, respectively. These transitions could be assigned to the dissociation of oligomers and to the cooperative unfolding of PDC-109 monomers, respectively. The modulation of the aggregation state of PDC-109 by its molecular environment and by phosphorylcholine binding suggests possible mechanisms for capacitation mediated by the seminal plasma protein.

The 2.4 A resolution crystal structure of boar seminal plasma PSP-I/PSP-II: a zona pellucida-binding glycoprotein heterodimer of the spermadhesin family built by a CUB domain architecture

The crystal structure of porcine seminal plasma spermadhesin PSP-I/PSP-II heterodimer has been determined in two crystal forms by multiple isomorphous replacement in an hexagonal crystal (space group P6(1)22) and molecular replacement in a trigonal crystal of space group P3(2)21. The crystal structure has been refined at 2.4 A resolution to an R-factor of 20.0% (Rfree = 25.9%) for 14,809 independent reflections with intensities greater than 2 sigma (I), with root-mean-square deviations of 0.009 A and 1.657 degrees from ideal bond lengths and bond angles, respectively. The final model includes 1688 non-hydrogen protein atoms of 221 amino acids and 79 water molecules. PSP-I/PSP-II represents the first crystal structure of a mammalian zona pellucida-binding protein. PSP-II displays a putative carbohydrate-recognition site located around its Asn50. This region shares structural features with sugar binding sites of known lectin structures of the leguminous and galectin families. PSP-I and PSP-II are N-glycosylated at asparagine residues 50 and 98, respectively, and show site heterogeneity. Only the innermost N-acetylglucosamine of PSP-I is defined in the crystal structure. Both subunits of the PSP-I/PSP-II heterodimer are built by a single CUB domain architecture. The CUB domain displays a novel fold, which consists of a compact ellipsoidal beta-sandwich structure (42 A x 27 A x 23 A) organized into two 5-stranded beta-sheets. Each sheet contains parallel and antiparallel beta-strands. Two disulphide bridges, which are conserved in all spermadhesin molecules and many CUB domains, crosslink loop LA and strand beta 4 and loops LE and LG, respectively, at opposite edges of the same face of the domain. The four highly conserved aromatic residues and 15 out of 17 invariant hydrophobic residues, which define the CUB domain signature, display an interior location, suggesting that this hydrophobic core may be essential for maintaining the overall folding of the domain. Most of the hydrophobic core residue characteristics are conserved in the jellyroll topology of certain icosahedral virus capsid proteins, indicating that the CUB domain and the viral proteins share a minimal structural core.

Crystal structure of acidic seminal fluid protein (aSFP) at 1.9 A resolution: a bovine polypeptide of the spermadhesin family

We report the three-dimensional crystal structure of acidic seminal fluid protein (aSFP), a 12.9 kDa polypeptide of the spermadhesin family isolated from bovine seminal plasma, solved by the multiple isomorphous replacement method and refined with data to 1.9 A resolution with a final R-factor of 17.3%. aSFP is built by a single CUB domain architecture, a 100 to 110 amino-acid-residue extracellular module found in 16 functionally diverse proteins. The structure of aSFP reveals that the CUB domain displays a beta-sandwich topology organised into two 5-stranded beta-sheets, each of which contain two parallel and four antiparallel strands. The structure of aSFP is almost identical to that of porcine spermadhesins PSP-I and PSP-II, which in turn show limited structural similarity with jellyroll topologies of certain virus capsid proteins. Essentially, topologically conserved residues in these proteins are those internal amino acids forming the hydrophobic core of the CUB and the jellyroll domains, suggesting their importance in maintaining the integrity of these protein folds. On the other hand, the structure of aSFP shows structural features that are unique to this protein and which may provide a structural ground for understanding the distinct biological properties of different members of the spermadhesin protein family.

Social work at the emergency department

We have evaluated the level of satisfaction of patients assigned to a social worker whose role was to give information, support, advice, grief and shock counselling; and develop resource strategies for marginal peoples. Six hundred patients were admitted to the study; 300 of them were supervised by a social worker (group A) and the other 300 were not (group B). After the completion of the study, a questionnaire was sent to be filled in by group A and group B for later evaluation. We collected 200 completed questionnaires (33.3%). The most important areas were: 105 patients (94.5%) in group A vs. 73 patients (82%) (p < 0.005) consider the medical care good or very good. The waiting time was assessed as short or acceptable in 91 patients (81.9%) in group A vs. 55 patients (61.8%) in group B (p < 0.001). The psychosocial care was assessed as very good or good in 101 patients group A (90.9%) vs. 73 patients in group B (82%) (p < 0.5).

HLA class I and class II allele distribution in the Bubi population from the island of Bioko (Equatorial Guinea)

We determined the HLA frequency distribution in a sample of 100 Bubi individuals born on the island of Bioko (Equatorial Guinea). HLA-A, -B and -C typing was performed by serology and PCR-SSP. DRB1/3/4/5, DQB1 and DQA1 alleles were determined by PCR-SSOP. The HLA allele distribution of this population group resembles those found in other Bantu-speaking groups; however, the higher frequency of A30, A32, B44, DRB1*1301 in the Bubi with respect to other Bantu groups and the absence of DR4 deserve special mention. The cloning and sequencing of class I and II genes in this population allowed the description of five new allelic variants: B*4407, Cw*0706, Cw*1801, Cw*1802 and DQB1*0612 and five confirmatory sequences: B*3910, B*5703, B*8101, Cw*1203 and Cw*1701. The following new HLA-C,B haplotypes have been found in Bubi: Cw*08-B*57, Cw*18-B*57, Cw*0302-B*53, Cw*07-B*53 and Cw*1601-B*63. The most frequent seven-locus haplotype is: A*30-Cw*17-B*42-DRB1*1102-DRB3*0202-DQA1*05-DQB1 *0301. In terms of genetic distance, the Bubi are closer to other Bantu groups than to West African populations.

Biliary lithiasis in the elderly patient: morbidity and mortality due to biliary surgery

BACKGROUND/AIMS

Diseases of the biliary tract are the most common conditions requiring intra-abdominal surgery in elderly patients. Complications and adverse outcomes of gallstones are more frequent in older people. The present study was undertaken to analyze factors that contributed to overall morbidity and mortality after open cholecystectomy. Laparoscopic surgery and other new techniques were compared with the open method.

METHODOLOGY

We studied retrospectively 76 patients that were 80 years and older. Each patient underwent operation in our unit. 40 patients had fewer than 30 days of clinical history, and 69 patients (90.8%) were emergency admissions. From a clinical point of view, 33 patients (43.4%) had jaundice on arrival and 21 (27.6%) fever. The operative findings included gallbladder wall infection in 46 patients (60.5%) and common bile duct stones in 25. Uni- and multivariate analysis was performed to discriminate variables in mortality and morbidity.

RESULTS

Nine patients (11.8%) died, and 38 had complications in the postoperative period. The main causes of death were pulmonary complications (4) and multisystem organ failure (3). Morbidity was mainly due to wound infection (14), urinary infection (13) and respiratory disease (10). Three variables influenced morbidity: sex (male), cardiovascular disease and jaundice upon admission. In the regression model only cardiovascular disease and jaundice were of independent influence. The mortality rate was associated with pre-operative jaundice.

CONCLUSIONS

Mortality and morbidity are related mainly to preoperative presentation. Jaundice is the main determinant of the outcome.

The crystal structures of two spermadhesins reveal the CUB domain fold

Spermadhesins, 12,000-14,000 M(r) mammalian proteins, include lectins involved in sperm-egg binding and display a single CUB domain architecture. We report the crystal structures of porcine seminal plasma PSP-I/PSP-II, a heterodimer of two glycosylated spermadhesins, and bovine aSFP at 2.4 A and 1.9 A resolution respectively.